Human Evolution
Classifying humans within the tree of life
Placental mammals
Monotremata
Marsupials
Carnivore - meat eating, large canines, whiskers
Rodent
Bats
Primates - fingers and thumbs
Hooved animals
Whales and dolphin
Rabbits
Anteaters and sloths
Elephant
Seals & sea lions
Tailed Primates = monkeys and lemurs
Non-tailed Primates = Apes = chimpanzees, gorilla, orangutan, and bonobos
Lactose tolerance
Going back in time, the last great notable adaptation in human kind was lactose tolerance. 9,000 to 7,000 years ago in modern day Iran, people first tried drinking cow's milk. Nowadays lactose tolerance is geographically distributed. 99% of people in Asia are lactose intolerant where as 90% of Europeans have tolerance.
https://youtu.be/ecZbhf96W9k
Neanderthals
Neanderthals were a subspecies of human that lived in Europe 40,000 years ago. They were shorter and stocky with a low bow and bigger noses than modern humans.
Neanderthals interbred with humans and today most Europeans have about 2% Neanderthal DNA. Most Africans don't have any.
Why are there black people?
The real question should be why are there white people or perhaps, why are there different skin colors?
Black people don't get sunburns as easily. Their skin acts as a defense against extended exposure to the suns rays.
According to current scientific consensus, modern humans originated in Africa 200,000 years ago. 100,000 they migrated out of Africa and into the middle east. From here populations split between Europe and Asia. If true, we all have African heritage.
The first Europeans are believed to have been black. The reduction of sunlight in Europe opposed to Africa meant that darker skin could absorb less vitamin D from the sun. This meant the darker someone's skin was the more they feel tired, weak or muscle pains. A long term deficiency of vitamin D leads to a disease called rickets. Rickets causes your bones to bend and break easily.
Therefore, lighter skin was naturally selected for. Those with lighter skin would absorb more of the sun and have more energy. If we look at a map you'll see that those closer to the equator have darker sin.
Race is an illusion. Gradient. All one race
Determined by sunlight
https://youtu.be/_r4c2NT4naQ
Wisdom teeth
The oldest human skulls have different shaped jaws from modern humans. Their jaws are noticeably wider. This is because they had more teeth than us. An extra 4 molars.
Scientists have a theory. Palentogists have been able to identify patterns consistent with man-made controlled fire. This comes on the eve of humans losing these teeth. Today we know these teeth as wisdom teeth. They develop later than the rest of your other teeth.
Wisdom teeth take until around your 25th year to push through. They no longer have and purpose other than causing pain. Infections? People can have anywhere between 0-4 wisdom teeth.
https://youtu.be/QQvlCZP-wTQ
Out of Africa
https://youtu.be/_ANNQKKwWGk
Appendix
The appendix is part of the large intestine. It's useful in providing good gut bacteria to fight the bad bacteria.
Appendicitis is when the appendix becomes infected. Untreated it swells and bursts inside the body and is often fatal.
About 5 to 9 of every 100 people develop appendicitis at some point. Before the development of effective surgery in the 18th century, half of people who got appendicitis died. The population of the USA is 330 million, without modern medicine half of about 7% of the population would die of appendicitis. That's 11 million deaths that are today preventable.
When people get appendicitis the surgery removes the appendix and the person goes on to live a normal life.
Goosebumps
Goosebumps have two observed purposes. The first is triggered when cold. The hair or feathers on an animal stand on end. This tension on their skin holds the hairs and feathers up and creates a canopy which traps air against the skin. The heat from the animals body warms the air and it insulates the creature. The animal then has a better chance of survival.
The second benefit is an adrenaline response. When sudden unexpected changes in emotion occur. This most commonly occurs in nature when an animal experiences fear. The response of goosebumps makes the animals hair stand on end and make it appear bigger than it is. Is does this in an attempt to defend itself.
https://youtu.be/MVnOBh9dTMA
https://youtu.be/_U5CHuJNrVI
Human Baldness & Narrow Hips
When humans began walking upright they began running. They're believed to have been long distance persistence hunters. They would chase their target through the Savannah for hours until it was tired and easier to catch. Sweating allowed humans too cool off quicker. Humans have 5 times as many sweat glands as chimpanzees.
Evolutionary adaptations involve trade-offs. The ability to run upright has led to the selection of narrower pelvis’. The narrower pelvis’ allowed humans to run better. However in mammals the pelvis is also the passage through which newborn babies pass, and the birth canal must be sufficiently large to accommodate a birth. Throughout history roughly 1% of births have resulted in the death of the mother. In 2020, 3.6 million babies were born. Without modern medicine, roughly 360,000 mothers would have died in birth. Instead, thanks to modern medicine only 0.238% of births result with the death of the mother. Children dying in childbirth is roughly thr same got the same reason, adding another 360,000 lives per year.
https://youtu.be/E76vqlhmBlc
Nipples
When I used to be a woman... and you
Nipples form very early on the human fetus. So early that the sex has yet to be decided. The human fetus starts with a female blueprint until the male hormones may or may not come in. Males have milk ducts down our chests just as women do. These ducts run parallel down the abdomen. The ducts follow the same designs as other mammals.
https://youtu.be/do4EjBeJ6bY
Wrist muscles
14% of the population has 1 less muscle than the others. Doctors will remove that tendon in certain surgeries because it has no effect on grip strength. The muscle is present but not useable in ground living primates like chimps and gorillas but always present in tree living primates like monkeys and lemurs.
Blind Spot
https://youtu.be/zjTCbL2wbRk
Conclusion
https://youtu.be/rFxu7NEoKC8
https://youtu.be/WD9AYN7JnFM
We weren't the goal of evolution. We're just as evolved as everything else. We're not better, we're just us. We're not the fastest, the strongest and our night vision is terrible. However, we've adapted to our environments to survive just as all of life is. We're suited to problem solving, eating a variety of foods, long distance running and our thumbs mean we can manipulate objects for our advantage.
Some things that were once advantageous to us are now harmful. Like the our cravings for sugary foods. For our ancestors such foods were rare and valuable. Now we have an overabundance and it's causing obesity. Another is back pain, a byproduct of our evolution to upright walking.
Similar to moths that once used stars to guide themselves through the night, they now die flying into bulbs.
However, humans bodies are good enough that without modern medicine, a portion of society can live to reproduce and the species survive.
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