Lecture 27 Flashcards
When did human evolution stop?
- it hasn’t
- natural selection should not be acting on you after you surpass the age of being able to reproduce because fitness is measured by the ability to produce offspring and if you can’t produce anymore it’s irrelevant
- NS doesn’t select on the body that’s aging and breaking down
- but we live well beyond our period of reproduction
Grandmother Effect
- grandmothers promote the reproductive success of their daughters by caring for their daughter’s young, thus promoting selection for their own post-reproductive survival
- parent shares 50% of their genes with offspring and 25% with grandchildren
- grandmothers active promotion of her daughter’s reproduction favors passing on the grandmother’s genes
- this can include genes that promote longevity
One Theory on Human Evolution
-it’s stopped in the hunter-gatherer stage and there has been so little time since the Neolithic when our habits changed to make an evolutionary difference
Paleo Diet
- says we evolved int he Pleistocene world and that is what we’re adapted to thus that’s how we should eat
- says anything else is maladaptive for us
- rooted in lies because it’s based on the idea that human evolution has stopped but it hasn’t
- genomic evolution has not slowed down after we stopped eating bison and such
Human Evolution Has Not Stopped
- we’re not hunter gatherers anymore
- human evolution has sped up since Neolithic Revolution
Human Discovery and Movement
- earliest homo sapiens date to 200,000 ya discovered in Africa
- modern humans migrated from Africa about 70,000 ya and remained hunter-gathers till Neolithic revolution 10,000 ya when agriculture was invented
- cattle raised for milk
- grain planted rather than wild vegetables and grains being harvested
- human habitation changed from sparse outdoors to crowded indoors
Long Range Migrations
- resulted in rapid changes in human culture
- humans displaced neanderthals
Skin Pigmentation
- long range migrations led to change in solar radiation which reduced the need for protection from UV and increased need for sun exposure to produce vitamin D
- first human to make migration from Africa were dark skinned
- skin color is genetically complex involving multiple genes for control of biochemical steps and gene sorting
Cows Milk
- revolutionary positive selection at an aspect of human metabolism that was initiated in the Neolithic Revolution
- neolithic agriculture quickly displaced older European hunter-gatherer people possibly because they could digest lactose which gave them an additional food source that hunter-gatherers could not exploit
- don’t do well with it in their ancestry
- genetically not really adapted to it
- developed lactase as adults to digest milk
- all children have it and as they grow up they lose it and can’t digest milk
Lactose Tolerance in Europe
- single nucleotide change in a gene regulatory site that controls the expression of Lactase
- independent mutations selected for in other regions where adults also consume milk products
- several independent alleles that yeild lactose tolerance
Lactose Tolerance In General
-looked at as an example of rapid evolution of human alleles co-incident with Neolithic revolution
Grain Farming
-consumption of starchy grains started during pre-neolithic
Living Indoors
- complex urban life emerges
- neolithic towns tightly packed with small buildings, and no streets and entry was through roof for safety
Crowded Urban Envrionments
- incredibly dense indoor space devoted to indoor biome in large city
- 50% of people now live in cities and it’s rising
Who lives with us in these indoor biomes?-intended
- pets
- microbes for fermentation
- houseplants
- humans
