Heredity
The Biological process that transfers the characteristics and traits from one generation to other (i.e. from parents to their children) is termed heredity. It is responsible for variation among the offspring and thus the evolution of a species over a period of time. Genes are the functional units of heredity that transfer character from parents to offspring. Example: the colour of skin or hair, eyes, height, etc.
Inheritance of Traits
The characteristics that are inherited from the parents are termed traits. An Inherited Trait is a particular genetically determined feature that distinguishes a person from another, the traits are inherited from one generation to other and this is the cause of the variations in population. For example, the colour of skin and eyes in humans. The set of genes is responsible for a particular character in a trait.
Allelic Relations
The genes are present as a pair for a specific trait. An Allele is a variant form of a gene. It is one or two more forms of a DNA sequence (a single base or a segment of bases) at a particular genomic location. Generally, an individual inherits two alleles, one from each parent, for given any genomic location where such variation exists. If the two alleles are the same the individual is homozygous for that allele and if the alleles are different the individual is heterozygous. Allelic heterogeneity refers to multiple mutations that occur in the same gene. Genetic variants determine phenotypic variability. Characterization of these allelic variations may open largely uncharted territory in genomics for biomedical research and may eventually lead to the discovery of the causative genes of usual hereditary diseases and their functionality of actions.
Rules for the Inheritance
Mendel’s Contribution
Gregor Johann Mendel referred to as the ‘Father of genetics, was an Australian Monk. He framed this law of Inheritance using his scientific and mathematical knowledge. Mendel did this experiment to understand the concept of heredity, His work laid the foundation of modern genetics. He used pea plants for his experiment as he found them easy to grow and they had a greater number of visible characteristics like tall/short, inflated/constricted pod shape, violet/white flower, and round/wrinkled seeds.
During his experiment, Mendel found that genes are the factors that control the expression of traits. Genes are present in pairs for a specific trait and they are termed alleles. Depending on the expression of traits the genes could be either dominant or recessive.
Pea plant in Mendel Experiment.
Dominant Traits: The traits that express themselves in the offspring in every possible combination and can be seen by the naked eye are called Dominant traits.
In Mendel’s experiment, the tall trait in the pea plants tends to express more than the small trait. Therefore, the tall trait of plants is said to be dominant over the small trait.
Recessive Traits: A trait which is not expressed itself in the presence of a dominant allele is known as a Recessive trait.
A recessive trait is expressed in an offspring when it is contributed by both parents. So, the recessive trait is present in an organism but cannot be seen due to the presence of the dominant trait.
The morphological expression of a single character which is observable physically is termed a phenotype. Examples – are tall or short, round or wrinkled seeds, the colour of a flower, etc.
The genetic constitution of the allele pair for a specific trait is termed as the genotype. Example – Tt or tt or TT.
Mendel was a mathematician so he used statistics to record the traits in each generation by using a statistical method known as Punnett square for predicting the possible genotype and phenotype in the offspring.
Monohybrid cross
A monohybrid cross is the hybrid of two individuals with homozygous genotypes. Only one character is considered. In this cross, Mendel showed the inheritance of dominant and recessive characters.
E.g. If a Round seed (RR) is crossed with a wrinkled seed (rr), we get 3 Round seeds and 1 wrinkled seed at the end of the F2 generation. The ratio of characters, arising after the cross at the end of the F2 generation is called the monohybrid ratio. In this case, the monohybrid ratio is 3:1. For the cross below the shape of the seed is considered.
Monohybrid cross
Dihybrid cross
A dihybrid cross is a cross between two individuals with two observed traits that are controlled by two distinct genes. In this cross, two characters are considered. The ratio of characters arising at the end of the F2 generation is known as the dihybrid ratio.
E.g. If a plant with a Round green pea (RRyy) is crossed with a plant having a wrinkled and yellow pea (rrYY), the first generation would have all-around yellow peas (RrYy). While crossing the same for an F2 generation, the result had greater variations and the new combinations were Green Round, Yellow round, yellow wrinkled and green wrinkled. Thus, the dihybrid ratio is 9:3:3:1.
Dihybrid cross
Sex Determination
The process of determining the sex of an individual, based on the composition of the genetic material is called sex determination. There is various mechanism that determines the sex of newborn organisms. In humans, the sex of a newborn child is determined by the genes inherited from the parents. There are generally 22 pairs of chromosomes in humans and one chromosome is the sex chromosome, which determines all the traits. In humans, the presence or absence of the Y chromosome determines the sex of an individual. Females have a perfect pair (XX) and males have a normal and the other short (XY) chromosome. All gametes formed by females and similar i.e. have X chromosomes. Males have two types of sperm i.e. half with an X chromosome and the other half with a Y chromosome. The sex of the baby will depend on fertilization. There are two possibilities.
Sex Determination.
Relation to the Theory of Evolution
The most fundamental and important aspects of biology are heredity and evolution, which are connected by inheritable features. These two terminologies assist us in learning and comprehending how the life cycle on Earth works. Both concepts are interrelated to one another, and there can be no evolution without heredity.
The transmission of properties from parent organisms to offspring is known as heredity. The evolution of a species is the outcome of changes in these specific inherited features over many generations that improve survival and reproduction chances. In other words, inheritable traits connects evolution to heredity.
Over several generations, the frequency of an inherited trait changed. Since genes determine characteristics, we can assume that over generations, the frequency of particular genes in a population changed. This is how evolution takes place in an organism
Significance of Heredity
- Heredity is considered an important factor in influencing the development of personality. It focuses on the transfer of half of his or her genes to the offspring.
- Heredity is the essential factor by which the offspring acquire the personalities, behaviours and characteristics of their parents and grandparents. These characteristics are passed through sexual or asexual reproduction.
- Heredity is the study of how parents pass down traits to their children through genes. The research conducted on heredity has helped in generating information in terms of various aspects of the theories of heredity.
- It indulges the interest of an individual towards acquiring positive traits as it will be an important contribution in bringing about improvements in their overall quality of life.
- Both parents contribute half of their genes with a different set of genes passed to different offspring. This creates diversity and variations among the offspring.
Basic Features of Heredity
- The basic concepts of heredity, derived by Gregor Mendel during his studies in the mid-19th-century became the foundation for the modern science of genetics.
- The transmission of traits from parents to their children is carried through genes, the functional units responsible for heredity in all living organisms.
- Many characteristics are influenced by more than one gene, they are referred to as polygenic. Many genes exist in multiple alleles throughout a population. The polygenic and multiple allelic nature of many traits gives a large potential for variability among hereditary characteristics.
- Heredity is the sum of all biological processes by which particular characteristics are transmitted between different generations.
- The sex cells or the gametes form the bridge across which the heredity must pass between the generations, and are usually invisible to the naked eye.
FAQs on Heredity
Question 1: Define Heredity.
Answer:
Heredity refers to the transmission of characters or traits from parents to their offspring. It is the continuity of features from one generation to other.
Question 2: What is the genotype of Human males and females?
Answer:
Genotype is the genetic constitution of an organism. In human beings, there are 23 pairs of chromosomes. Out of these 22 chromosome pairs are called autosomes and the sex chromosome is the last pair of chromosomes that help in deciding the gender of that individual. The genotype of the human male is 44 + XY and the Genotype of the human female is 44 + XX.
Question 3: What is an Allele?
Answer:
Allele is an alternative form of a gene occupying the same position on a chromosome and affecting the same characters but in two alternative ways. It is a variation of the same sequence of nucleotides at the same place on a long DNA molecule. The genomic location of any gene or any genetic material is called a locus and the alternative DNA sequences at a locus are called alleles.
Question 4: State the difference between the dominant trait and the recessive trait.
Answer:
A dominant trait is an inherited character that appears in an offspring if it is contributed by a parent having a dominant allele. A dominant trait overrides the effect of a different variant of the same gene on the other copy of the chromosome.
A trait that must be contributed by both parents in order to appear in the offspring is termed a recessive trait. This trait is expressed only when the genotype is homozygous. When an organism has two recessive alleles it tends to be expressed in the offspring.
Question 5: State the Monohybrid ratio and Dihybrid ratio.
Answer:
Monohybrid Ratio:
- In the F1 generation, the ratio is 100% hybrid type.
- In the F2 generation: the phenotypic ratio is 3:1 and the genotypic ratio is 1:2:1.
Dihybrid Ratio:
- In the F1 generation, the ratio is 100% hybrid type.
- In the F2 generation: the phenotypic ratio is 9:3:3:1 and the genotypic ratio is very complex.
Question 6: Why sexual reproduction produces more variation?
Answer:
In sexual reproduction, two different sets of chromosomes from both parents are mixed resulting in a completely new set of chromosomes. They also undergo crossing over during gamete formation and thus each gamete formed is unique. Hence the progeny has more variation. A large set of characteristics is inherited from both parents and is together passed on to the next generation causing diversity among the individual in the next generation.
Inheritance
For instance, when a single bacterium divides, it creates two new bacteria, which then split once more to create four new bacteria. Due to minute mistakes in the DNA replicating process, the newly created individuals would be remarkably similar to one another and would only differ slightly from one another. In terms of asexual reproduction, this is the case.
Greater individual variation can be seen when it comes to sexual reproduction. A species’ chances of survival in the environment are not the same for all of these modifications. Their potential mostly depends on how variations or evolution will play out. Different people benefit from different things.
Drosophila, which has a high thermal tolerance, will, for instance, survive a heat wave better. The source of the evolutionary process is thus determined in this case by the environmental conditions that select for particular variations. The process by which features, and qualities are reliably inherited is determined by a similar pattern and the laws of heredity, even though there are still a few overt effects of reproduction that affect subsequent generations of people.
Parents Pass on their Characteristics to their Children
When two parents reproduce sexually, their genes are used to pass on traits, which are genetically defined features, to their offspring. This genetic data is carried by DNA, which is present in our cells’ chromosomes.
How do these Traits get Expressed?
The traits are expressed as the genotype, which is the organism’s genetic makeup, and the phenotype, which is how those qualities manifest physically.
For example, tallness and dwarfness might have contrasting characteristics depending on the height of the plant. In contrast to dwarfism, the trait of tallness is indicated by a distinct genotype. As a result, the tall and dwarf characteristics of plants are their phenotypes, while the genes that cause them are their genotypes.
Expression of qualities
Genes are based on the inheritance of an individual’s chromosomal characteristics. The chromosomes contain the genes, which can be expressed as a visible trait depending on the type of gene in the organism.
The functional proteins that aid in expressing the organism’s outward appearance is produced by the gene once it has first been translated to mRNA through transcription. As a result, the gene’s ability to produce proteins aids in the development of particular phenotypes. The information needed to make proteins in the cell comes from cellular DNA. The gene for a protein is a segment of DNA that contains the necessary instructions to make that protein.
How do proteins regulate the traits?
Let’s use being tall as an example of a characteristic. We are aware that hormones in plants can stimulate growth. Thus, the amount of a specific plant hormone may affect plant height. The effectiveness of the manufacturing process will determine how much plant hormone is produced. Now think about an enzyme that is crucial to this procedure. The plant will grow tall and produce a large amount of hormone if this enzyme functions effectively.
Both parents must contribute equally to the progeny’s DNA during sexual reproduction if the interpretations of Mendelian experiments that we have been considering are true. If both parents can influence a trait in the offspring, then both parents must be passing on a copy of the same gene. This implies that each pea plant needs to have two sets of all the genes, one inherited from each parent. Every germ cell in order for this mechanism to function needs to have the same gene set.
Central Dogma
The phrase “the Central Dogma” was created by Francis Crick to describe how information moves from nucleic acids to proteins. DNA-encoded information is translated into RNA, which then produces a protein’s linear amino acid sequence. Although transcription and reverse transcription allow for the reversible transfer of information between DNA and RNA, no mechanism for changes in the amino acid sequence of a protein to cause an equivalent change in the RNA or DNA has yet been discovered.
DNA to RNA
- DNA is translated into RNA.
- The RNA polymerase enzyme reads the DNA strand serving as a template before creating an RNA molecule whose bases are complementary to the DNA strand.
- RNA is made in the same way as DNA, 5′ -> 3′, and RNA polymerase reads DNA templates 3′ -> 5′.
The “coding” strand of DNA shares the same nucleotide sequence as RNA, with the exception that uracil (U) is present in RNA instead of thymine (T). - In order for RNA polymerases in prokaryotes and eukaryotes to recognize the beginning of genes, DNA-binding proteins called transcription factors must attach to specific sequence motifs in the DNA called promoters.
- Just “downstream” of the promoter, transcription is initiated when transcription factors enlist RNA polymerase to attach to the promoter sequence.
RNA to Protein
RNA to protein translation: Translation happens by using an mRNA molecule as a template to create a protein. There are three main elements needed to convert an RNA base sequence to an amino acid sequence in a protein:
- Messenger RNA (mRNA): Protein-coding genes allow for the synthesis of mRNA. (Genes encoding rRNAs and tRNAs are examples of other types of genes that do not encode proteins.)
- Ribosomes: Large assemblies of ribosomal RNA molecules (rRNAs) and several proteins make up ribosomes. When they are not functioning, they split into two parts, the small and large subunits, each of which contains an rRNA and a number of proteins. The fact that the catalytic region for the peptidyl-transfer reaction—which involves adding additional amino acids to the expanding polypeptide chain—is made entirely of rRNA astounded scientists when the structures of bacterial ribosomes were identified at high resolution. As a result, the ribosome is not an enzyme but rather a massive ribozyme, or a catalytic RNA molecule supported by several proteins.
- Transfer RNAs (tRNAs): that are “charged” with their respective amino acids or carrying those amino acids in addition to them. The amino acid and the mRNA codon are matched by tRNAs. The nucleotides in an mRNA codon complement the bases in the anticodon loop. A high-energy link between the relevant amino acid and the 3′ ends of the tRNA exists. Amino-acyl tRNA synthetases are a family of enzymes found in cells that identify different tRNAs and “charge” them by attaching the proper amino acid.
- The ribosomal small subunit and a unique initiator tRNA carrying the amino acid methionine start translation towards the 5′ ends of the mRNA. Most of the time, translation starts at the AUG triplet nearest to the mRNA’s 5′ end. The tiny subunit of the ribosome simply “scans” from the 5′ ends of the mRNA until it locates the first AUG codon in eukaryotes. In prokaryotes, the ribosome normally attaches to a certain sequence, “positioning” the ribosome at the initial AUG. Translation always starts with an AUG codon (methionine) in both prokaryotes and eukaryotes. The big ribosomal subunit then docks.
- New tRNAs with complementary anti-codons to the mRNA codons and the associated amino acids come when the ribosome advances three bases at a time along the mRNA from the 5′ to the 3′ direction. To connect the amino acid to the carboxyl end of the expanding polypeptide chain, a peptide bond is formed. The empty tRNA is ejected to make place for a fresh aminoacyl tRNA as the ribosome travels another three nucleotides.
- Additionally, the polypeptide chain produced by the ribosome possesses directionality; one end of the chain has a free amino group, while the other end has a free carboxyl group. These are referred to as the N- and C-termini, respectively. Polypeptide chains lengthen from the N-terminus to the C-terminus because new amino acids are only added to a free carboxyl end.
FAQs on How these Traits get Expressed
Question 1: Describe heredity.
Answer:
The passing down of genes, characteristics from one generation to the next is referred to as heredity.
Question 2: Describe evolution.
Answer:
Evolution is a process in which changes in heritable genes or characteristics of biological organisms, over a very long time.
Question 3: What is stated in the Law of Segregation?
Answer:
According to the law of segregation, each diploid person has two alleles (copies) of a certain trait.
Question 4: Why are learned characteristics not inherited?
Answer:
Over the course of their existence, organisms acquire qualities. Since these features are a result of non-reproductive tissue, they cannot be passed forward.
Question 5: Describe a gene. Where do genes reside?
Answer:
DNA fragments are referred to as genes which carry all the genetic information. Genes are located on chromosomes.
Evolution
Over successive generations change in heritable characters in population is called evolution. Genes are passed from parents to offspring through reproduction and through genes, these characteristics are expressed. When the processes like natural selection and genetic drift occur in a population then evolution takes place. Heritable characters constantly over generations as the characters which are common or rare in a population are decided by evolutionary pressure which changes constantly. Variations that are seen at all levels i.e., at the level of species, biological organization, organisms, molecules, etc. are the result of evolution.
Natural selection has three ways to determine whether the organism is fit for survival or not i.e., behavior and structural traits vary among populations, the Rate of reproduction and survival differs among individuals, and fit traits can pass from generation to generation. Through the evolution of this method, we can determine which offspring are more able to survive in a population. So, to survive in the respective scenario the fit traits are passed on to the next generation which leads to variations in the characters of the individual which ultimately leads to evolution. Through the evolution of the species i.e., by passing on the useful characters and leaving behind the useless characters, we can able to see the present biodiversity around us which is the result of the same process.
Sex Determination
The process of determining of the sexual characteristics of an individual is known as sex determination. Usually, there are two sexes when an offspring is born through sexual reproduction. Hermaphrodite character is seen in some species in which both male and female organs are present in one individual. When a female reproduces without fertilization i.e., through parthenogenesis then it gives birth to offspring of one sex only. Sexual characters or sexual morphology can be determined by different genes or different alleles. Usually, the process of sex determination is a genetic process. Due to the different combinations of chromosomes, different sexes originate like XY, ZW, XO, etc. The Domino effect is followed as there is one main gene called a sex locus which differentiates the sex of an organism and the other genes follow it. Through variations in environment sex of the fetus can be determined. Nowadays, there is no such system that can determine the sex of the fetus accurately but in the future to be 100 % sure about the sex of the child in a worm they are developing such systems which can analyze initialized signals of reproduction through which they can tell the sex of the offspring in worm accurately. These systems will also clarify hermaphrodite individuals who have fully or partially male and female reproductive organs. In ancient times this technique was developed to cure genetic and hormonal diseases in fetuses. As there are many hormonal and genetic diseases that can not be cured after birth but through the technologies, those diseases can be cured inside the worm. In this technique cells from the worm are taken and tests are carried out through which the sex of the fetus is determined along with any diseases that it carries. But later on, people start misusing this technique by abording the girl child. As the misuse of this increased the government banned this technique and now the tests are done but the sex of the fetus is not revealed.
XY/XX Sex Chromosomes
It is usually found in humans and also in mammals and in some insects. Males have XY chromosomes in this system whereas the female has the same set of chromosomes i.e., XX. The size and shape of these chromosomes are different. In fruit flies, the sex is determined as the egg gets fertilized while in humans the sex is determined lately.
XO/XX Sex Chromosomes
Male only carry one chromosome i.e., XO while the female carries the XX chromosome in this system of sex determination. The absence of a chromosome is determined by O. Across the two chromosomes, the number of genes that get expressed will tell us about the sex of the offspring. Usually, this system is observed in crickets of Orthoptera order, cockroaches from Blattodea, insects, grasshoppers, etc.
ZZ/ZW Sex Chromosomes
This system is seen in some reptiles, some insects, birds, etc. In this system, the male is identified as having two same sets of chromosomes i.e., ZZ while the female carries a ZW set of chromosomes. DMRT1 in chickens is found to be responsible for the expression of these genes. The chromosome which is smaller means it carries important characters while the other one that is large carries less important characters.
Frequently Asked Questions
Question 1: Give the importance of evolution and heredity?
Answer:
Heredity determines the traits which passes on to the next generation. It is responsible for passing the new and fit traits to the next generation while evolution is important for the change in population. Variation is very important part of population as the environmental conditions changes rapidly so for the species to survive in respective changing environment it is very important for them to evolve accordingly.
Question 2: Is heredity important to humans. If yes, then why?
Answer:
Yes, heredity is very important for humans because the fundamental and structural unit of our genome is gene and gene is carried through the process of heredity. Moreover, our whole genetic makeup, our behavioral activities are the results of the genes that are carried by heredity from our parents. So, it won’t be wrong if we say that all the characters and the whole personality of an individual is the result of heredity.
Question 3: Explain a method by which the sex of human offspring can be determined.
Answer:
Each parent gives one chromosome to the offspring. From the mother, one X chromosome is received as the mother carry a set of the same XX chromosome whereas from the father either X or Y can be received as the father carry a set of different chromosome i.e., XY. It is not wrong to say that the sex of offspring can be determined by the chromosome that the offspring received from his father. If the offspring is having XX set of chromosome then it’s a baby girl and if the offspring carry XY then it will be a baby boy.
Question 4: Explain the sex chromosome and tell us the pair of sex chromosomes present in human beings.
Answer:
Chromosome that differs from other chromosomes in shape, size, and behavior which is heterotypical chromosome, allosome, and idiochromosomes known as sex chromosomes. In human, only one pair of sex chromosomes are present which are typically mammal allosomes. There is a difference between autosomes and allosomes i.e., allosomes are different from one another due to which they determine sex like XY is a set of chromosome which are different from each other due to which they determine the sex whereas autosomes are same pair of chromosomes which are same in both male and female.
Question 5: Give the difference between the homogametic and heterogametic sex determination systems.
Answer:
Usually, there are two types of systems by which we can determine the sex of offspring i.e., the homogametic sex determination system which has similar gametes, and the heterogametic sex determination system which carries different gametes. Both systems can be seen in all living organisms. The organisms in which have homogametic system is seen in female i.e., seen in human beings, insects, true bugs, grasshoppers, cockroaches, roundworm (XX), produces one type of eggs (A+X) whereas in organisms where females shows heterogametic system like in reptiles, birds, moths, butterflies produces two different types of eggs (A+W), (A+Z). Same goes for males where they show homogametic system produces one type of sperms (A+Y) i.e., in human beings and where they show heterogametic system in cockroaches there produces two types of sperms (A+X), (A+Y).
Big Bang Theory
Regarding the beginning of humankind and its various forms, the Big Bang Idea is the most widely accepted theory. The universe, according to the hypothesis, would be created more than twenty billion years ago as a result of a tremendous explosion. The genesis of the earth took an additional 10 billion years. The circumstances for life, including the temperature and environment, stabilized as the earth grew. It is estimated that the life i.e, the first would be on earth appeared roughly two billion years ago (mya).
It is considered that the first cell formed from non-cellular molecules but there would be no evidence for the evolution of the first living cell. More of these were created when this cell split. A few distinguishing characteristics of the developing cells enabled them to survive. These characteristics include the capacity of the cells to release oxygen as well as the ability to capture light energy and energy derived from it. At last, simple unicellular creatures underwent a great deal more sophisticated multicellular organism formation.
Evolution moved along considerably more quickly with the emergence of multicellular creatures. Between 500 and 300 million years ago, a variety of new creatures, including invertebrates, plants, and animals like reptiles, fish, amphibians, and mammals, underwent additional development and evolution (mya). Later, these organisms began to develop in unique ways. This started the lineages’ bifurcation. That was greatly influenced by environmental factors including changing climate, scarcity of resources, predators, etc. One living form predominated over the others during each stage of evolution. Therefore fittest of all would be chosen by nature to predominate over the others.
Before plants ( three twenty million years ago) colonized the continents, then jawless fish (three fifty million years ago). Plants were later replaced by fish, which could survive on both land and water and consumed them. These lobefin animals gave rise to amphibians, which later transformed into reptiles. During that many mya, reptiles of various sizes, forms, and life cycles flourished. Some, like Ichthyosaur( two hundred million years ago), were aquatic, while others were terrestrial. At that time, dinosaurs were well-known land reptiles. They went extinct for unidentified reasons. After reptiles, there came a period when mammals predominated over all other animals.
Causes for Evolution
Evolution can occur via different mechanisms-
Mutation
Changes in a living organism’s DNA sequence are referred to as mutations. Future generations are only affected by mutations that affect germ cells, which are egg or sperm cells. All of a person’s cells carry these mutations throughout their lifetime, which are inherited from their parents. These mutations are what cause evolution. Only some cells contain the acquired mutations, which take place during the course of a person’s life. These are brought on by external sources like UV radiation and do not affect the next generation. They don’t belong to evolution.
Gene flow
It would be defined as Gene would flow from the population to the population. For instance, pollen is transported from one location to another by the wind or by people that relocate to new towns or nations. A gene transfer takes place when a person from one country relocates to another and mates with someone there. This is how genes spread among various populations. Gene transfer can occur horizontally, which refers to the asexual transmission of genetic material from one population to another. Prokaryotes frequently experience this phenomenon.
Genetic Drift
It describes the shift in an individual population’s allele frequency as being due to chance. The impact of this random occurrence is greater in populations that would be small and less so in bigger groups. It is of two types one is the founder effect and the other is the bottleneck effect.
The bottleneck effect happens when a population suddenly declines as a result of environmental causes.. In this situation, the population loses certain genes. As a result, the original gene pool’s genetic variety is drastically reduced. This implies that the genetic make-up of the remaining population diverges from the original population’s.
The founder effect would be of Genetic diversity is lost when a new population is made up of a few isolated individuals from a larger population. Therefore prior population is not present in them. This causes some genetic features to predominate over others, which causes hereditary illnesses in subsequent generations.
Natural Selection
Some people are more likely to survive and reproduce than others if they possess particular features. These genetic traits are passed down to their progeny, resulting in an evolutionary change in succeeding generations. Natural selection is the process of choosing the genetic traits that will help future generations survive. One well-known illustration of natural selection is Darwin’s Finches. Depending on their adaption and dietary preferences, Darwin’s finches have developed into fifteen different species.
Need for Evolution
Understanding evolution has been crucial for searching for and also would use the resources which come from nature like fossil fuels, and it will continue to be so as human civilizations work to create interactions with the environment that are sustainable. These instances can be multiplied countless times.
Conceptual Question
Question 1: What does “natural selection” mean?
Answer:
Natural selection is the process i.e, an adaptation of the organism takes place and transforms itself in large populations.
Question 2: Into how many species of finches develop?
Answer:
According to Darwin, those would be fifteen, known as Darwin finches, which tell about Natural selection.
Question 3: Types of the Genetic drift?
Answer:
One would be the founder effect and the other one would be the bottleneck effect.
Question 4: First life would be on?
Answer:
First life would happen approximately twenty billion years ago.
Question 5: Plants would emerge on?
Answer:
They would emerge approximately
Three hundred to five hundred million years ago.
Question 6: Explain the phenomenon which help in Evolution?
Answer:
These would be of four types: natural selection, genetic drift, gene pool, and mutation.
Acquired and Inherited Traits
The variations occur in sexual reproduction or due to some minor errors in DNA copying. Let us consider that under a shade of bushes there live some 12 beetles. Due to some variations, one of the Beatles is green, and the other Beatles are red. Also considered that these Beatles will produce sexually, leading to variations. Consider that crows will eat these Beatles. The green-colored battles are camouflaged by the bushes due to the green color of the bushes. The red-colored ones are easily identified by crows and are eaten. In this course of process, the red-colored Beatles will extinct eventually. Latest imaging another situation where in the green colored species of Beatles are produced as a result of variance and are living with the red colored Beatles. Imagine an elephant group passes nearby and the elephant’s foot accidentally falls on the group of red beetles and all the red beetles died. As the beetle population increases again, most Beatles found are green colored ones. Let us consider another scenario where due to some drought situation all the Beatles living under the shade of that bushes how become so weak and thin that this situation continues for a few generations. If the drought conditions are sensed and if it starts raining once again if the bushes grow properly which are the food sources for the Beatles, then the Beatles will grow stronger and fitter than they were before drought conditions.
In the first case scenario, the color change gave an additional advantage of survival. This was a naturally selected variant. The green beetle population growth due to the evolution which is directed by natural selection.
But in the second scenario, there was no survival advantage due to the new variant. It was an accidental incident which led to the extension of red-colored beetles. So, in smaller populations, it is more common than changes occurring due to DNA being more frequent.
In the third scenario, we have seen that the shape of the body is restored when they get enough food like earlier. This can’t be called a variation.
Theory of natural selection
Charles Robert Darwin (1809-1882) is the first scientist who brought the thought of acquired and inherited traits for the first time. When he was 22 years old, he went on a voyage for 5 years to South America, the Islands of South America and its coast. During his voyage, he conducted tests on a variety of life on earth. He continued these tests even after returning to England. He conducted several experiments before producing his own hypothesis that evolution occurs due to natural selection. Furthermore, he did not know how variations occurred in species.
Acquired traits
In sexually reproducing organisms, there is a specialized reproductive tissue called as germ cells. The changes occurred in the DNA of germ cells can only be transferred to the next generations. In the third scenario, we have seen earlier that low weight is not a character that is going to be inherited. Even if the Beatles will have low weight for few generations due to scarcity of food, the stronger beetles will be found once the drought conditions are over. What about changes occurring to our body cells other than self or not going to be transferred to the next generation.
Latest try to understand this concept with another good example. Let us breed a few mice for our experimental purpose. Let us cut the tails of these mice for a few generations. Even if we continue this process for up to 50 generations or more, the character of mice giving birth to younger mine with tails is not going to change as the changes are not made in the joint cells by cutting the tails of mice.
Thus, we can state that acquired characters are not transferred to the next generations.
Inherited traits
Acquired traits are the characteristics which are transferred from parent generations to the next generation. Acquired characters include hair color, body complexion, eye color etc. These characters are transferred through DNA. Due to some crossover or sexual reproduction if any of the character gets altered this will be stored in the DNA of germ cells which will be transferred to next generation and this character will be expressed in the upcoming generations.
Inheritance of characters from parents is equally contributed by both males and females. Expression of these characters depends on the genes we get. Gregor Johann Mendel (1822-1884) has given a greater contribution by his experiments on garden peas. He chooses garden peas for the hair experiment because he could find seven characters with alternative expressions.
Let us take the parent generation of a garden pea for our experiment. Let us consider the character height. The height has two alternatives, namely tall and short. If we cross-breed these two parent generations in the first F1 generation, we won’t get short character expressed at all. This is because in the F1 generation we get genes of both tall and short height, but the short character is suppressed and the dominant character of tall is expressed. If we cross-breed these F1 generation peas and if we observe the characters in the F2 generation, we can observe the short characters’ environment. This is because the characters we acquire are expressed.
Choosing Parent generation for reproduction which will have TT genes for tall and tt genes for short height character.
| Parent | t | t |
| T | Tt | Tt |
| T | Tt | Tt |
Choosing F1 generation for reproduction. F1 generation will have genes Tt for height Character.
| F1 | T | t |
| T | TT | Tt |
| t | Tt | tt |
Thus, the short character is expressed in 25% of the Plants in F2 generation.
Difference between Acquired and Inherited traits
| Sl No | Point of Difference | Acquired traits | Inherited traits |
| 1 | Definition | These are the characters which are acquired by an organism in the lifespan between its birth and death as a response to the changes in environmental. | These are the characters which are inherited from the parental generation and will pass to the next generation through DNA. The information incorporated in genes. |
| 2 | Controlled by | These traits are not controlled by genes. | These traits are controlled by genes. |
| 3 | Changes occur in which cells | The changes that are occurring in somatic cells are called as acquired trades and are not going to be transferred. | The changes that are occurring in the zoom sales are called as inherited traits and are going to be transferred to the next generation. |
| 4 | When do these characters observe | This can be seen in a life period between birth and death. | This is present by birth. |
| 5 | The type of variation | This type of variations are called as somatic variations. | These types of variations are called genetic variations. |
| 6 | Environmental response | These traits are affected by environmental changes. | These traits are not affected by environmental changes. |
| 7 | Examples | Educational knowledge, Technical skills etc. | Hair color, eye color etc. |
Conceptual Question
Question 1: What are acquired characters?
Answer :
The characteristics are expressed due to some change in the environment or some accident that are present only in the generations which are acquired during their life. These characters are not going to transfer to the next generation as these changes are not recorded in the DNA sequence.
Question 2: What are inherited characters?
Answer :
The characteristics that the younger generations get from the parent generations through genes are called inherited characters. These characters will be passed on to upcoming generations if there is no change due to variation. This character or stored in the form of information in the DNA sequence of germ cells.
Question 3: What is natural selection?
Answer :
Due to some changes in the environment, accidents or some variations sum of the organisms of species of a population cannot survive and are going extinct eventually. This process is called natural selection.
Question 4: What is the reason for not a transfer of characters that are acquired during life?
Answer :
The acquired characters are present to the existing generation only. The changes occurring in the body of living organisms are not going to store in the DNA of germ cells. Only the changes present or made in the DNA offer germ cells are going to pass to the next generation.
Question 5: Why In the F1 generation of garden peas in the experiment conducted by Mendel did the character short not expressed?
Answer :
In the F1 generation even if both the genes present were carrying the character of both tall and short height the short character did not appear because in the garden peas the height character tall is the dominant character and can easily suppress the short height character. Due to the dominance of the tall height character the short height character is suppressed and is not expressed in the F1 generation.
Question 6: Explain with an example of natural selection.
Answer :
Let us consider that under a shade of bushes there live some 12 beetles. Due to some variations, one of the Beatles is green in color and the other Beatles are red in color. Also considered that these Beatles will produce sexually leading to variations. Consider that crows will eat these Beatles. The green-colored battles are camouflaged by the bushes due to the green color of the bushes. The red-colored ones are easily identified by crows and are eaten. In this course of process, the red-colored Beatles will extinct eventually.
Speciation
Speciation is the development of one or more species from an existing species. It occurs when two populations are isolated( both geographically and reproductively) leading to almost no gene flow between the two populations.
However, inbreeding continues within the isolated populations producing more and more generations. Eventually, the members of these two groups will be incapable of reproducing with each other even if they happen to meet. In other generations, the genetic drift accumulates different changes in a subpopulation. Also, natural selection may also operate variably in these different geographic locations. For example, in the territory of one sub-population, crows may get eliminated by eagles.
But this may not be the case in the other sub-population, whereas as a result, the crow numbers will become very high. As an outcome of this, the green variation will not be selected at the first site, while it will be strongly selected at the second.
Together, the process of genetic drift and natural selection may make two isolated sub-populations more and more different from each other. This will lead to the generation of new species.
These new species may be developed:
- If DNA changes are severe enough, such as change in the number of chromosomes, eventually the germ cells of the two groups cannot fuse with each other.
- If a new variation emerges in which females are only able to mate with a few males due to their specific traits. This allows very strong natural selection for that trait.
Types of Speciation
- Allopatric Speciation: In this type of species formation, a part of the population becomes geographically isolated from the main population. An example of Allopatric Speciation is Darwin’s finches which lead to the theory of evolution.
- Sympatric Speciation: This type of speciation occurs between populations occupying the same geographic range. This type of speciation is common in herbivore insects when a new plant is introduced into a geographic range of species.
- Parapatric Speciation: It separates adjacent populations. Parapatric speciation takes place when a population of a species enters a new niche or habitat. When a portion of a surrounding has been polluted, the type of speciation that occurs is known as parapatric speciation. Polluted environments include mining activities that leave waste with high amounts of metal such as lead and zinc.
Factors Influencing Speciation
- Genetic Drift: Genetic drift is also known as the “Sewell Wright Effect”. It is random in gene(allele) frequency. It occurs only by chance. It is nondirectional. Genetic drift can cause the elimination of certain alleles or fixation of the other alleles in the population. It refers to a change in the population of alleles in the gene pool.
- Natural Selection: The selection by which organisms are more likely to survive and reproduce is known as Natural Selection. It eventually leads to speciation. Natural selection is the process through which populations of living organisms adapt and change.
- Mutation: A mutation is a change in the DNA sequence of an organism. Mutations can result from errors in DNA replication during cell division, exposure to mutagens, or a viral infection.
- Geographic isolation: The physical separation of members of a population. populations may be physically separated when their original habitat becomes divided.
- Recombination: Recombination, the process by which DNA strands are broken and repaired, producing new combinations of alleles, occurs in nearly all multicellular organisms and has important implications for many evolutionary processes.
- Hybridization: Hybridization occurs almost inevitably during speciation. Moreover, studying patterns of introgression across the genome, and the spatial structure of hybrid zones, can tell us much about the genetics of divergence and reproductive isolation.
Important Characteristics of a Species
The important characteristics of a species may be summarised as follows.
- All the members whether present in one or more populations found in different and even remote areas of the globe are derived from a common ancestor.
- The members resemble one another more than they resemble individuals of other species.
- There is a complete anatomical similarity.
- All the members of a species have a similar karyotype.
- There is a broad similarity in morphological characters.
FAQs on Speciation
Question 1: What is Speciation?
Answer:
Speciation is the splitting of one species into two or more new species or the transformation of one species into a new species over time.
Question 2: What factors could lead to the rise of a new species?
Answer:
The main factors which lead to the rise of new species are natural selection, genetic drift, geographical isolation, and mutation.
Question 3: What is allopatric speciation?
Answer:
In this type of species formation, a part of the population becomes geographically isolated from the main population. An example of Allopatric Speciation is Darwin’s finches which lead to the theory of evolution.
Question 4: Which type of speciation is based on the observation of H.L. Carson on Drosophila inhabiting Hawaii islands?
Answer:
Quantum speciation is based on the observation of H.L. Carson.
Question 5: Define Mutation.
Answer:
A mutation is a change in the DNA sequence of an organism. Mutations can result from errors in DNA replication during cell division, exposure to mutagens, or a viral infection.
Evolutionary Relationships
A common ancestor between two different organisms can be inferred from essential traits that they share. These similarities can be used to define evolutionary connections. In order to establish evolutionary relationships and identify patterns amongst organisms, an evolutionary tree or phylogeny is crucial. The following traits are helpful in determining evolutionary relationships:
- Breeding behavior
- Geographical distribution
- Cladistics
- Structural similarities
- Biochemistry
Evolution and Classification
According to the theory of evolution by natural selection, genetic variety and the principle of the fittest lead to changes in organisms through time. Modern biology is built on this notion, which is supported by data from a wide range of scientific fields.
Organisms can be categorized as a technique of grouping them according to similarities. The Linnaean system, created by Swedish scientist Carl Linnaeus in the 18th century, is the most popular classification scheme. The Linnaean system is based on the binomial nomenclature concept, which gives each species a two-part name. The genus appears in the first half of the name, and the species appears in the second.
Fossils
Typically, when an organism dies, its body will degrade and disappear. The body, or at least some of it, may occasionally be in an environment that prevents decomposition, completely. For instance, a dead insect that is entangled in heated mud will not break down rapidly, the mud will gradually solidify and preserve its shape. the appearance of an insect’s body parts. All of these traces that have been preserved of living creatures are referred to as fossils.
Fossils are Helpful in Developing Evolutionary Relationships
Thousands of extinct animals’ fossil remains have been found and researched by paleontologists over the years. This fossil record demonstrates that numerous extinct species had different forms than any of their living relatives. The record also illustrates how organisms changed over time in succession, allowing us to discern how they changed from one form to another.
When an organism passes away, it is typically broken down by other living things and by weathering processes. When an organism dies, certain of its body parts, especially the hard ones like shells, teeth, or bones, are sometimes maintained because they are buried in mud or otherwise shielded from the environment and decomposing organisms. They eventually become petrified and are permanently preserved with the rocks they are lodged in.
The earth was formed over 4.5 billion years ago, according to techniques like radiometric dating, and the earliest fossils resemble creatures like bacteria and cyanobacteria. These microbes have fossils in rocks that date back more than 3.5 billion years. The earliest animal fossils, which are little, soft-bodied organisms resembling worms, are from the Ediacaran fauna and are almost 700 million years old.
The earliest vertebrate fossils indicate that they initially appeared about 400 million years ago, while the earliest mammals arrived about 200 million years later. The fossil record isn’t comprehensive, though. Paleontologists have only managed to retrieve and study a very small portion of the fossils that are still present on Earth, and in those few instances, the succession of forms has only occasionally been precisely rebuilt. The evolution of the horse is one illustration.
Carbon Dating
One of the most common techniques in archaeology for dating organic artifacts up to 50,000 years old is carbon dating. This approach is predicated on the notion of the carbon-14 isotopes’ long-term radiative degradation. Physics has shown that the pace at which radioactive compounds degrade depends on the atomic number and mass of the atoms that are decaying. The ratio of radioactive isotopes to the estimated initial concentration of these isotopes at the moment of the organism’s death can be used to calculate the approximate age of the decaying material using this constant. According to scientists, there hasn’t been much of a shift in the ratio of carbon-12 to carbon-14 isotopes in the atmosphere, therefore their connection should mostly remain unchanged.
Importance of Carbon Dating
Different civilizations and faiths use various dating techniques. Absolute dating, or the age of the substance prior to the present, is a particularly useful feature of carbon-14 dating. This implies that it can be applied and evaluated against dates everywhere in the world. In fact, it is still the primary method for dating the last 50,000 years and is regarded as the “most important development in absolute dating in archaeology.” Scientists seek to use this instrument to solve the puzzles surrounding the origin of mankind, the duration of his existence, his travels, and the construction of a timeline of human history.
DNA Sequence Determination
The nucleotide sequence of DNA is its most crucial component. Utilizing DNA polymerase’s enzymatic properties allows for the determination of DNA sequences. All DNA polymerases need a primer to start the synthesis process. A single primer is hybridized into the DNA strand that has to be sequenced to start the sequencing reaction. This primer-initiated synthesis starts out exactly like a PCR. The primer used to start the synthesis process can either be a primer used in PCR to amplify the DNA or it can be complementary to the vector in which the DNA is cloned. The fact that every newly generated molecule will have the same sequence is crucial for sequencing DNA. DNA polymerase is combined with deoxynucleoside triphosphates to lengthen the primer. All of the newly expanded molecules would be complementary to the complete template chain if these two elements alone made up the reaction mixture, just like in PCR. In addition to the four deoxynucleoside triphosphates (dNTPs), the sequencing reaction also includes 2′,3′-dideoxynucleoside triphosphates, or ddNTPs (ddGTP, ddATP, ddTTP, or ddCTP).
Excavation
Excavation is the act or process of digging, particularly when a specified object is being taken out of the ground. To find artifacts and fossils, archaeologists conduct excavations.
Although there are many different kinds of excavation, they all involve making holes in the ground. Excavation is necessary for mining coal, gold, or diamonds, and it is frequently necessary to perform some excavation prior to pouring a foundation for buildings and dwellings. Excavare, “to hollow out,” with its roots in ex-, “out,” and cavare, “to hollow,” is where the Latin word excavation, which means “a hollowing out,” comes from.
Classification of Excavation
A common method of classification is by the material being excavated:
- Topsoil excavation: In order to do this, the exposed layer of the earth’s surface must be cleared of any vegetation or decomposing debris that would cause the soil to become compressible and hence unfit for supporting structural loads. Although the depth varies from site to site, it typically ranges from 150 to 300 mm.
- Earth excavation: This entails removing the soil that lies immediately below the topsoil. The excavated material, sometimes known as “spoil,” is frequently heaped up and used to build foundations and embankments.
- Rock excavation: This is the removal of material that cannot be dug up without the aid of specialized excavation techniques like drilling (either manually or with large gear) or explosive blasting.
- Muck excavation: This is the process of removing overly damp debris and soil that cannot be piled.
- Unclassified excavation: This involves removing a combination of the aforementioned components, typically in situations when it is challenging to tell which materials have been present.
FAQs on Tracing Evolutionary Relationships
Question 1: What are the tools for tracing evolutionary relationships among species?
Answer:
Tools that are responsible for tracing evolutionary relationships among species are-
- Studying the similarities and differences between several species to identify traits from a common ancestor.
- Evidence for the emergence and diversification of species from a common ancestor can be derived from studying fossil remains of ancient forebears.
- It is possible to identify shared genes and genetic material in related creatures by comparing the DNA sequences of other organisms.
Question 2: What is carbon dating?
Answer:
Carbon dating is one of the most popular methods in archaeology for determining the age of organic artefacts up to 50,000 years old. This strategy is based on the idea of the long-term radiative destruction of the carbon-14 isotopes. Physics has revealed that the pace at which radioactive materials disintegrate depends on the atomic number and mass of the atoms that are decaying. This constant can be used to determine the approximate age of the decaying material by comparing the ratio of radioactive isotopes to the estimated initial concentration of these isotopes at the time of the organism’s death.
Question 3: What is excavation?
Answer:
Excavation is the act or process of digging, particularly when a specified object is being taken out of the ground. To find artifacts and fossils, archaeologists conduct excavations. Although there are many different kinds of excavation, they all involve making holes in the ground. Excavation is necessary for mining for coal, gold, or diamonds, and it is frequently necessary to perform some excavation prior to pouring a foundation for buildings and dwellings.
Question 4: Define DNA Sequence Determination.
Answer:
The most important part of DNA is its nucleotide sequence. DNA sequences can be determined by using the enzymatic capabilities of DNA polymerase. A primer is required by all DNA polymerases to initiate the synthesis process. The sequencing procedure is initiated by hybridising a single primer to the DNA strand that has to be sequenced. Just like a PCR, this primer-initiated synthesis gets underway. The primer used to initiate the synthesis process can be either complementary to the vector in which the DNA is cloned or it can be a primer used in PCR to amplify the DNA.
Question 5: What are the homologous organs? How do they help in providing evidence for organic evolution?
Answer:
Homologous organs are defined as having distinct activities but sharing a common embryogenic origin, embryonic development, and interaction with surrounding organs. They represent a tight bond between their owners. For instance, although the structure and function of a human forelimb, a bird’s wing, a horse’s leg, and a seal’s flipper may appear to differ from one another, they are all built using the same pentadactyl structure, with the same number of bones, muscles, blood vessels, and nerves arranged in the same pattern and developing similarly. Therefore, the most logical theory is that all of these animals’ forelimbs were passed down from a single ancestor over a very long time.
Question 6: What are fossils? How do they act as evidence for organic evolution?
Answer:
Fossils are the skeletal remains of extinct plants, animals, or other species that have been petrified. When plants or animals are buried in mud and soil, they are created. By leaving the hard bones and shells, the soft tissues decompose quickly. Over time, sediment accumulates on top of the bones and shells, hardening to form rock. The history of evolution can be directly demonstrated by fossils. Scientists use fossils to compare modern and historical creatures. An estimate of the occurrence of an organism during a specific period can be gained from calculating the age of fossils.
Human Evolution
Humans are being evolved gradually, the course of development includes a progression of changes that can make those species either adjust to the ongoing climate or become wiped out. Charles Darwin’s – ‘On the Origin of Species, in which he composes his hypotheses of evolution by natural selection, is one of the main works of logical concentrate at any point distributed. Development is viewed as the consequence of changes that are being made in the genetic material of people Ardipithecus was perhaps the earliest ancestor.
Characteristics of Evolution
- The skulls are more modest in size than that of the current man.
- The volume of the brain ran between 600-700 c.c.
- The brow was higher than in chimps and the face was jutting.
- The forehead edges were unmistakable.
- The occipital condyles were ventrally positioned
- The back of the skull was round in shape.
- They have huge jaws with little incisors.
- It additionally had enormous and spatulate canines
- They had huge cheek teeth.
Stages of Evolution
Man has originated through several stages and these stages are explained below
Dryopithecus
Dryopithecus is from Europe 12.5 to 11 million years ago (Mya). Being the earliest known ancestor of man is thought of. It is found in 1856, they were additionally tracked down in certain pieces of Africa, Asia, and Europe. Dryopithecus relocated south from Europe or Western Asia into Africa. It has been realized that the evolution of man started with him.
Australopithecus
They as evolved in eastern Africa around 4 million years ago. There are different types of Australopithecus species present, including Australopithecus anamensis, Australopithecus afarensis, Australopithecus robustus, and Australopithecus africanus.
- Australopithecus anamensis – lived around 3.8 to 4.2 million years ago, the oldest species.
- Australopithecus afarensis – lived around 2.9 to 3.9 million years ago in east Africa
- Australopithecus robustus – lived around 0.87 to 2.2 million years ago in southern Africa.
- Australopithecus africanus – lived around 3.6 million years ago.
Homo Habilis
Homo habilis lived around 1.4 Ma.to 2.8 million years ago. The name homo habilis in Latin signifies ‘handyman’. They made tools from stone and bones which got the name. They were upstanding. Homo habilis was adjusted to living on trees.
Homo Erectus
Homo erectus was found in 1891, on the Indonesian island of Java. They used to possess a bigger brain and they are upstanding. Additionally, may have utilized fire to cook meat. Homo erectus lived around 1.8 million years to a long time back. Homo erectus utilized instrument tools including quartz, made of bones and wood. Homo erectus are cave occupants, they have diminished intestinal length and they are in a bigger populace.
Homo neanderthalensis
They lived around 400,000 to 28,000 years ago, in Europe and Asia. Neanderthals additionally possessed altogether bigger brains and weight. Neanderthal variation to cold conditions. Likewise, they had an enormous head and jaw and were exceptionally strong and solid. They were carnivores and the instrument tools from the period demonstrate they were trackers. They were likewise cave occupants yet their caverns were more agreeable and they lived in gatherings and chased after food gatherings.
Homo sapiens
Homo sapiens is the early modern humans. The word sapiens is Latin which signifies ‘wise’ or ‘smart’. Home sapiens had fostered the power of thinking unlike Neanderthals and stone tools advancements created. They were omnivorous and had the option to deliver workmanship. Their brain size was diminished to 1300 cc. The jaws are very diminished and the skull was adjusted, and the jaw showed up. They assembled food through hunting.
Frequently Asked Questions
Question 1: Who developed the first tools?
Answer:
Homo Habilis was the first man to foster tools. This species of human addresses a halfway stage between the Australopithecus and Pithecanthropus erectus. The name homo habilis in Latin signifies ‘handyman’. They made tools from stone and bones which got the name. They were upstanding. Homo habilis was adjusted to living on trees.
Question 2: What are the features of the Peking man?
Answer:
The highlights are:
- The skull was little and the cerebrum volume was 850-1300 c.c.
- The skull was low-vaulted.
- The forehead edges were bold.
- The engraving of the brain proposed the capacity for discourse.
- Indications of carries out of quartz and different rocks have been found.
- The hearths showed the utilization of fire.
Question 3: Who is Homo sapiens?
Answer:
Homo sapiens are the main species on our earth which is the consequence of more than 7 million years of evolution. The word sapiens is Latin which signifies ‘wise’ or ‘smart’. They were omnivorous and had the option to deliver workmanship. Their brain size was diminished to 1300 cc.
Question 4: Give some discoveries of ancient human fossils.
Answer:
Here some of the discoveries of ancient human fossils are
- One lower jaw of Homo heidelbergensis was found in 1907 in a sandpit at Mauer, Germany.
- The remaining parts of skulls and portions of the skeletal construction of Pithecanthropus were found up to 1943 in the Mid-Pleistocene caves at Choukoutien, China.
- The remaining pieces survived from Pithecanthropus erectus were found in the Mid-Pleistocene of Solo River close to Trimil, Java from 1891 until 1945.
- The remaining parts of the hominids were found in the Mid-Pleistocene, South Africa in 1925.
Question 5: What are the stages in Human evolution?
Answer:
Man has originated through several stages and these stages are explained below –
- Dryopithecus
- Australopithecus
- Homo habilis
- Homo erectus
- Homo neanderthalensis
- Homo sapiens
Question 6: What order does a human belong to?
Answer:
Humans have a place with the family which is known as the Hominidae of the order Primates. Apes like people additionally have a place with the exact order that is Primates. With the progression of time, the precursors of this order developed and they began turning out to be increasingly unique. It is accepted that the very first predecessors of people started in Africa and in the end, moved towards Asia, Europe, and the remainder of the world.
Question 7: Describe Homo Neanderthalensis.
Answer:
Homo Neanderthalensis are cave inhabitants and they made stone instrumental tools and weapons. There was likewise proof of the utilization of fire. They are gigantic and long and have level topped skulls. The forehead was subsiding with weighty brow ridges. The jaws were distending yet the jawline was retreating and they had huge teeth. The period is assessed about 100,000 years back.