18. Human Evolution

What animals are included in order primates?

many forms

• over many millions of years, primates diversifed into many of the forms we see today

• Many remaned arboreal some less so

• Most lived in some kind of social group

• the eveouinary lineage that gave rise to modern humans is part of the ape clade

Hominins, the clade that incules moder & extinct humans arrose 5.5 MYA

Early hormin speices had key difference from other primates

The linear depction of human evoeultn from chip to moder human is

INCORRECT

Humans did not “evolve from” modern apes; we share a comoon ancestor

• Humans and our cloeset primate realtives (chims) share a common ancestory that lived arround 5.5 MYA

• Moder humans arrose areoun 200 kYA in ear Africa (possibly in Botwana which was then a vast wetland

Ape Phylogeny

Fossil-calibarted molecuelar clock data suggest that thehuman and chimpanzee liengaes split 5.5-7 million years ago

there are thousands of fossils of

early hominins

A keay feautre of the eveoultion of apes was an increase in brain size and complexity

• the realtive brain size and complexity of apes is far greater thatn other primate speices

• varius hyptheses for why this may have occeured

• - living in complx social groups

• - changes in diet

• - envriomental variabtiliy

Homo sapiens

• kingdom: Animalia

• phylum: chordata

• class: mammalia

• Order: primates

• Family: homindae

• Gensu : homo

• Speices: homo sapines

Hoe are members of the genus Homo unque form other rpiamtes

Apes: large cerebrum, no tail

• homo spp

• Bipedal and more erect psotures

• smaller canine teeth

• non opposable grasping toes

• physically weaker, slower

• less hiar

• glta-on projecting face

• larger brain

• too making/use

• spoken langague and culture in homo sapines

Moder humans co-existed with closely realted archaic humans

• other closley realted groups of humans existed in places that modern humans were found

• these groups know as “arachaic humans” co-exited with humans

• the most well known o f these are Neanderthls and Denisovans

It has recently become possible to directly sequence DNA fom ancient bone

• with moder DNA tech, we can now sequence DNA from anice samples

• Samples over 100kYA can be sequeces

• teeth and the core of spefic types of bone are good soruces of ancient DNA

We have complete genome sequecnes from both Neadnerthals and Denisovans

• Using acnecnt DNA techniques, reaserahces full seqeunce the genmoe of a Neanderthal and a Denisovan indiuvdal

• We can compare these genmoes to modern human genmoes

Arhcaic human DNA is found in all moder human populations todsy

Neanderthal varaitns are presertn in 23andMe customers

Modern human genetic diversity is largely a hold-over of anicent geographic patterns

Historricaly human populations were limted to realtive small geographi areas

this resultes in a small number of unque traits'/alleles that exist in soome population s and not others

the overshwelming majority of genetic varation is ahred among all populations

Only a few human traits show evidence of adaption to local envrionemntets

• there are only a very small number of conssitnet genetic differences between human populations

• nearly all are the reslut of geneti drift, i.e. not adaptive

• howerver there are a small number of traits that do show evidence of adaption in huans

• skin color

• Lactase persistence

The amount of UV radation exposure from the sun varies over the surface of the earth

Human Pigemntation is a tradeoff between cost/benefits in differnt envrionemtns

Human Pigemntation is a tradeoff between cost/benefits in differnt envrionemtns

• lighter skin allows more vitamin D sythenese at lower UV but deplets folate and increases cancer risk when UV is high, most benefical at lower UV

• Darker skin portects form UV, but can result in lower vitamn D availibty if sunligh is limiting

• mostly nenbfical at higher UV

What are the compnenet in the milk produced by female mamalls or women while nursing?

• Protein: The main proteins in human milk are casein, alpha-lactalbumin, lactoferrin, lysozyme, and secretory immunoglobulin IgA. 

• Carbohydrates: The main carbohydrate in human milk is lactose. 

• Fats: Human milk fats include cholesterol, triglycerides, short-chain fatty acids, and long-chain polyunsaturated (LCP) fatty acids. 

• Minerals: Human milk contains minerals expressed as ash. 

• Vitamins: Human milk contains vitamins, including folate, choline, and vitamin C. 

• Immunoglobulins: Human milk contains immunoglobulin, mainly secretory immunoglobulin A (sIgA), which protects against infection. 

• White blood cells: Human milk contains white blood cells, which can kill microorganisms. 

• Oligosaccharides: Human milk contains oligosaccharides, which prevent bacteria from attaching to mucosal surfaces. 

Lacatse persistence evolved indepdently in African and European populations

The ability to digest lactos as an adult (lacatse persistnece) vaires strongly geoegraphilcy_ mos people in african and in the middle east exhibit lacatse persistence