Revision summary
Erect posture frees the hands for tools and carrying. It favours endurance walking and a high visual field. Costs include lumbar strain, difficult birth, and venous problems. The obstetric dilemma pits a narrow pelvis against a large brain. Selection kept the bargain because making and ranging paid.
Model answer
Copper italics in this answer — like this — are the key facts. Each one is unpacked in the Facts & figures rail.
Introduction
Bipedal erect posture is the hominin hallmark. It freed the hands and strained the spine, pelvis, and birth canal. Gains and losses are one design.
Body
Gains
- Hands free for tools, carrying, and gesture. Washburn and Darwin already tied bipedalism to culture.
- A high, scanning eye-line and endurance walking, later used by Homo erectus on open landscapes.
- Thermoregulation in savanna sun is argued: less surface to noon radiation, more sweating skin.
Losses
- Lumbar lordosis, slipped discs, and osteoarthritis of the lower back and knees.
- A narrow pelvic inlet versus a large neonatal brain: the obstetric dilemma, with rotational birth and risk to mother and child.
- Inguinal hernia, varicose veins, and haemorrhoids from vertical viscera and valves.
- Foot arches and fallen arches; a locked knee that saves energy but fails in injury.
Balance
- Natural selection kept the posture because foraging and making paid more than a perfect back.
Flow diagram
flowchart TD BP[Bipedalism] --> G[Hands tools endurance] BP --> L[Spine pelvis veins feet] L --> OB[Obstetric dilemma]
Conclusion
Erect posture bought tools, range, and a scanning stance. It cost backs, births, and veins. The human body is that bargain.
Quick related
Students also ask
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Explain the skeletal changes due to erect posture and their implications.
Next question on this syllabus topic (2016 · Q8(c)). View answer →
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Was bipedalism for running first?
Early hominins walk. Endurance running is clearer later, with erectus-grade bodies.
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Can culture remove the losses?
Midwifery, chairs, and surgery mitigate. They do not rewrite the skeleton.
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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2016 · Q8(c) · Anthropology GS 1 · 15 marks
Explain the skeletal changes due to erect posture and their implications.
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