In 1859, Charles Darwin wrote a book called On the Origin of Species, explaining the theory of evolution involving natural selection. Evolution is the process how living things change over time, which causes changes in physical traits. Such changes could allow an organism to survive, live in the environment and produce offspring. Physical changes may not be as obvious as they were in the past, but they have happened within human and will continue to happen. Five different forces have influenced human evolution are nutrition, mutation, climate, fire, and technology. Nutrients help you grow taller, build strong muscles, and have healthy skin.
Before heating and cooking food, all humans got their food by gathering, fishing, and hunting. When farmers began domesticating animals, there was a lot of sources of milk and meat such as sheep, cattle, and goats but also of new infectious diseases. A lot of farmers shrank in structure because they suffered from iron deficiency and developmental delays. Our faces, jaws, and teeth have gotten much smaller, and our DNA has changed since the invention of agriculture. 10,000 years ago, cattle began being domesticated, then infants no longer needed to digest their mother’s milk. Unfortunately, infants stopped making enzyme lactase, which breaks down lactose into simple sugars. Then lactose tolerance developed among infants in Europe, the Middle East, and Africa.
Mutation creates slightly different versions of the same genes, called alleles. Charles Darwin proposed that all living species came from common ancestors. People who have blue eyes can discover their past family back to one person. Professor Eiberg said human eyes default color is brown. Brown eyes happen from increase of melanin, which is a dark skin pigment. A gene known as OCA2 appeared in northern Europe. OCA2 is a mutation that melanin production in the iris of the eye and caused the eye color to become blue and not brown. OCA2, the genetic mutation, affects the gene in the chromosomes which does not produce brown eyes by creating the switch. As people of different eye colors breed with other people, the mixture of these different traits produce a new shade of eye color. 29,000 years ago, light skin gene called SLC24A5 developed which is common to Europeans and Middle East.
Humans began moving into different climates from Africa. Paleobiologists can see human ancestors evolving and moving to other parts like Europe by designing early types of DNA from Africa. Around two million years ago, the climate in east Africa changed into big forested areas into grasslands because it dried up. A lot of people have different face and body structures which helps them adapt to their environment, for example the Eskimos have a small height and squat bodies with ideal proportions for heat conservation. Also, the Negroes have wide and short noses which helps release water vapor. However, a long and narrow nose would help in heat protection in cold climates. Fire makes heat but also does mechanical processes that help you chew such as chopping and grinding. Cooked foods can kill bacteria and makes it less time for people to eat since it is more soft”. After food has heat up, there are more nutrients will help the brain to develop. Cooking not only gave early humans the energy they needed to improve the brain size but also helped them get more calories from food so that they could gain weight. Early humans had much greater upper body strength and longer arms for hunting and making stone tools.
Over time, we’ve become less reliant on muscular strength for our survival. Since early humans gotten more nutrients and started using their hands more, it had helped them use their hands more accurately. By using hands we invented further tools that help us to hunt and survive. A study found that leaning your head 60 degrees is the same as putting 60 pounds of pressure on your neck. Previous research also shows that sitting in front of our computers all day can also negatively affect our stature. grasping your phone too much – could cause muscle tension or irritate current conditions like tendonitis. Early humans had more flexible, stronger, and physically bigger muscle structures because they had to fight, hunt, run and hide. The human brain has tripled in size the last five million years, but most of this growth occurring in the past two million years. We do not need the intelligence in order to survive, since we have all the technological tools for it. The size of our ancestors brains was the size of other apes alive today. Although our brain does have a lot tasks such as intelligence, emotion, and creativity. The brain controls function of many organs within our body, memory and speech, thoughts, movement, and the function of many organs within our body.
In conclusion, five different forces have influenced human evolution are nutrition, mutation, climate, fire, and technology. I believe Darwin’s theory of evolution is more evidential because it explains how species evolved formed from their ancestors. An example would be the DNA structure of humans and chimps. The DNA tells us that human are 98.8% the same as chimpanzees. Also Darwin stated that principle of natural selection are organisms that adapt to their environment are more likely to survive and leave more offspring.
When Darwin was studying wildlife, he noticed the variation of appearances in different animals such as the mice’s fur that lived on rocks, tortoise, penguins and birds from different island have different physical structures on different islands. Later on he found out that each species developed their own physical structures through the environment of the island.
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