Revision summary
Microevolution is allele-frequency change in a population. The forces are mutation, selection, drift, gene flow, and non-random mating. Macroevolution is speciation and higher-level pattern in deep time. Punctuated equilibrium and regulatory genes are debated extras, not magic. Hominin splits and isolate drift show both scales in anthropology.
Model answer
Copper italics in this answer — like this — are the key facts. Each one is unpacked in the Facts & figures rail.
Introduction
Microevolution is change in allele frequencies within a breeding population. Macroevolution is the origin of higher taxa, species, and long-term trends. The same genetic mechanisms scale up, with debate about extra rules.
Body
Microevolutionary mechanisms
- Mutation supplies new alleles. Most are neutral or harmful; a few are useful, as in lactase persistence.
- Natural selection changes frequencies by differential survival and fertility. Sickle-cell and malaria is the human classroom case.
- Genetic drift, including founder effect and bottleneck, is strong in small groups. Andaman and other island isolates illustrate drift and founder sampling.
- Gene flow mixes populations. Migration prevents full local fixation.
- Non-random mating, including inbreeding and assortative mating, changes genotype frequencies and can raise homozygosity.
To the macro scale
- Speciation is the hinge. Allopatric isolation, then reproductive barriers, turns micro change into new species. Hominin fossils show this as splitting lineages, not one file.
- Macroevolution adds origin of bauplans, mass extinction, and adaptive radiation. Gould and Eldredge argued punctuated equilibrium: long stasis, then geologically rapid change, still built from genetic processes.
- Chromosomal rearrangements and regulatory (Hox) shifts can produce larger morphological jumps than a single point mutation. They remain genetic mechanisms.
Unity and caution
- The Modern Synthesis treated macro as accumulated micro. Palaeontology adds time, extinction, and development. Anthropology uses both for fossils and living variation.
Flow diagram
flowchart TD MIC[Microevolution] --> M[Mutation selection drift flow mating] MIC --> SP[Speciation] SP --> MAC[Macroevolution taxa trends] MAC --> F[Fossil hominin splits]
Conclusion
Mutation, selection, drift, flow, and mating rules drive microevolution. Speciation, radiation, and developmental-genetic change carry those mechanisms into macroevolution.
Quick related
Students also ask
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Is macroevolution a different kind of genetics?
Mostly the same forces over longer time, plus speciation and developmental architecture.
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Does drift create new species by itself?
Drift changes frequencies. Isolation and reproductive barriers are needed for speciation.
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
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2026 · Q2(b) · Anthropology GS 1 · 15 marks
How do religious beliefs help people to devise cultural mechanisms to adapt to their environment? Discuss in detail with appropriate examples -
2016 · Q3(b) · Anthropology GS 1 · 15 marks
Discuss different social control mechanisms in simple societies.
More from this topic
Q7(a) · UPSC Mains 2022 · Anthropology GS 1 · 20 marks · Solution
Discuss the role of evolutionary forces in creating human diversity
Synthetic theory of evolution
Four genetic forces plus culture make human diversity. Mutation invents; selection sorts; drift rumples small groups; flow mixes. Malaria and dairying are gene–culture cases. Indian data show both isolate drift and long-range mixture. Races as types fail; clines and histories hold.