Genetic changes in human ancestors have determined "advantages" in modern life.
Humans are probably the most curious species ever. We have brains much larger than those of other animals that allow us to build utensils, understand abstract concepts and use language. But we also have few hairs, weak jaws, and are slow to give birth.
How does evolution explain this extravagant creature? Check out:
1. Live in a group
30-60 million years ago
The early primates, a group that includes apes and humans, emerged shortly after the dinosaurs disappeared. Many quickly began living in groups to better defend themselves against predators, and this required each animal to "negotiate" a network of friendships, hierarchies, and enmities. As such, group living may have boosted intellectual capacity.
2. More blood in the brain
10-15 million years ago
Humans, chimpanzees and gorillas all descend from an unknown and extinct hominid species. In this ancestor, a gene called RNF213 evolved rapidly and may have stimulated blood flow to the brain by enlarging the carotid artery. In humans, RNF213 mutations cause Moyamoya disease - a carotid narrowing that leads to deterioration of brain capacity due to poor brain irrigation.
3. The division of primates
7-13 million years ago
Our ancestors separated from their chimpanzee-like relatives about 7 million years ago. At first they looked very similar, but inside their cells were on the march. The ASPM and ARHGAP11B genes mutated, as did a segment of the human genome called HAR1. It is not yet clear what caused these modifications, but ARHGAP11B and HAR1 are associated with cerebral cortex growth.
4. Sugar 'Spikes'
Less than seven million years ago
After the human evolutionary line split from the chimpanzee line, two genes mutated.
SLC2A1 and SLC2A4 form proteins that carry glucose into and out of cells. These modifications may have diverted glucose from the muscles to the brain of primitive hominids and may have stimulated organ growth.
5. Skillful hands
Less than 7 million years ago
Our hands are incredibly skilled and allow us to build tools or write, among other activities. This may be due in part to a DNA fragment called HACNS1, which has evolved rapidly since our ancestors and chimpanzee ancestors split. It is unknown what exactly HACNS1 does, but it has contributed to the development of our arms and hands.
6. Weak jaws: more room for the brain
2.4 - 5.3 million years ago
Compared to other primates, humans cannot bite too hard because they have weaker muscles around the jaw as well as smaller jaws. This seems to be due to a mutation of the MYH16 gene, which controls muscle tissue production. The mutation occurred at least 5 million years ago. Small jaws may have made room for brain growth.
7. Varied Diet
1.8 - 3.5 million years ago
Our earliest primate ancestors ate mostly fruits, but later species like the Australopithecus expanded their menu. In addition to eating a wider variety of plants, we eat herbs, eat more meat, and even cut it with stone tools. More meat led to more calories and less chewing time.Continues after advertising
8. Naked, naked with his hand in his pocket
3.3 million years ago
The humans are almost naked. The reason is unknown, but this occurred between 3 and 4 million years ago. It is suspected that hair loss occurred in response to the evolution of parasites such as ticks. Exposed to the sun, human skin darkened and from then on all our ancestors went black until some modern humans left the tropics.
9. An intelligence gene
3.2 million years ago
A gene called SRGAP2 has been duplicated three times in our ancestors, and as a result brain cells would have developed more connections.
10. Larger Brains: Thinking Primates
2.8 million years ago
Humans belong to a group or genus of animals known as Homo. Homo's oldest fossil was excavated in Ethiopia and is 2.8 million years old. The first species was possibly the Homo habilis, although scientists disagree with this argument. Compared to their ancestors, these new hominids had much larger brains.
11. Complicated childbirth: a very large head
At least 200 thousand years ago
For humans, childbirth is more difficult and dangerous. Unlike other primates, mothers almost always need help. Walking on two legs made human females have a narrower pelvic canal, and passing a human baby with the larger head of its ancestors was hampered. To compensate for this "logistical problem," human babies are born small and defenseless.
12. Fire Control
1 million years ago
No one knows when humans learned to control fire. The earliest evidence of fire use is in the Wonderwerk Cave in South Africa, which contains fossilized ashes and burnt bones dating back a million years. But some experts say that being able to process food longer than that could include cooking.
13. The Gift of Speech
600,000 - 1.6 million years ago
All the great hominids have air sacs in their vocal tract, allowing them to make loud shouts. But not humans, because these bags make it impossible to produce different sounds. Our ancestors apparently lost their air sacs before evolutionary separation from the species. Neanderthal, which suggests they could talk too.
14. A gene for language
Half a million years ago
Some people have a mutation in a gene called FOXP2. As a result, it costs them to understand grammar and pronounce words. This suggests that FOXP2 is crucial for learning language usage.
15. Enhanced Carbohydrate Saliva
Farmers' descendants have more copies of the AMY1 gene
Human saliva contains an enzyme called amylase, made by the AMY1 gene, that digests starches. Modern humans whose ancestors were farmers have more copies of AMY1 than those whose ancestors were hunters, for example. This digestive enhancement may have helped usher in cultivation, villages and modern societies.