Here are the main points in English:
Why do humans walk heel-first? Did this help humans spread across the world from Africa?
- Humans typically walk by placing the heel on the ground first, followed by the rest of the foot and the toes.
- Scientists believe this walking style is a distinctive feature that helped humans travel long distances and eventually spread from Africa across the globe.
- However, heel-first walking also increases stress on the bones and joints, leading to evolutionary adaptations in the human body.
The Research
- Researchers from Penn State University studied the walking patterns of humans and chimpanzees.
- Their findings were published in the journal Proceedings of the National Academy of Sciences (PNAS).
- Using modern motion-analysis and force-measurement technologies, they compared how humans and chimpanzees walk.
Humans vs. Chimpanzees
- Chimpanzees, when walking on two legs, often place the side of the foot on the ground first.
- Humans almost always land on the heel first.
- Scientists suggest that this difference allows humans to walk much farther and more efficiently than chimpanzees.
Advantages of Heel-First Walking
- Landing on the heel helps propel the body forward more efficiently.
- This makes long-distance walking less energetically costly.
- The ability to travel long distances may have been crucial for early humans searching for food, hunting, and migrating into new environments.
The Trade-Off
- Heel-first walking increases impact forces on the legs and joints.
- As an illustration, Professor Nathan Thompson explains that when people try to walk quietly across a creaky wooden floor, they tend to walk on their toes because toe-first contact reduces impact and noise.
Human Evolutionary Adaptations
Scientists believe humans evolved several adaptations to cope with the increased forces caused by heel-first walking:
- Thicker heel bones
- Larger knee joints
- Other skeletal changes that improved endurance walking
Connection to Human Expansion
- Early humans often had to walk long distances while hunting and gathering food.
- Heel-first walking made long-distance travel more efficient.
- This likely contributed to humans’ success as endurance walkers and helped them expand from Africa into diverse environments around the world.
Key Conclusion
The study suggests that heel-first walking was an important evolutionary adaptation that improved long-distance walking efficiency, helping humans become exceptional travelers and hunters. Although it increased stress on the skeleton, evolution compensated through stronger heels, larger knees, and other anatomical changes.