Lecture 27

Question 1

When did human evolution stop?

Answer 1

• 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

Question 2

Grandmother Effect

Answer 2

• 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

Question 3

One Theory on Human Evolution

Answer 3

-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

Question 4

Paleo Diet

Answer 4

• 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

Question 5

Human Evolution Has Not Stopped

Answer 5

• we’re not hunter gatherers anymore

- human evolution has sped up since Neolithic Revolution

Question 6

Human Discovery and Movement

Answer 6

• 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

Question 7

Long Range Migrations

Answer 7

• resulted in rapid changes in human culture

- humans displaced neanderthals

Question 8

Skin Pigmentation

Answer 8

• 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

Question 9

Cows Milk

Answer 9

• 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

Question 10

Lactose Tolerance in Europe

Answer 10

• 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

Question 11

Lactose Tolerance In General

Answer 11

-looked at as an example of rapid evolution of human alleles co-incident with Neolithic revolution

Question 12

Grain Farming

Answer 12

-consumption of starchy grains started during pre-neolithic

Question 13

Living Indoors

Answer 13

• complex urban life emerges

- neolithic towns tightly packed with small buildings, and no streets and entry was through roof for safety

Question 14

Crowded Urban Envrionments

Answer 14

• incredibly dense indoor space devoted to indoor biome in large city
• 50% of people now live in cities and it’s rising

Question 15

Who lives with us in these indoor biomes?-intended

Answer 15

• pets
• microbes for fermentation
• houseplants
• humans

Question 16

Unintended Introduction

Answer 16

• human pathogens and parasites
• arthropods
• human-associated microbes
• rodents
• birds
• bats
• other mammals
• reptiles

Question 17

Microbiomes of Our Bodies

Answer 17

• made up of bacterial phyla
• more of the cells of our bodies are bacterial than human
• which leads to our resistance to disease
• selection is strong in crowded environments in which pathogens will be easily transmitted
• people with long history of town living show more resistance to TB and leprosy than those urbanized for shorter times

Question 18

Neolithic Revolution

Answer 18

• led to more recent selective changes like
• reduced UV exposure: selection for lighter skin
• animal domestication and husbandry; consumption of milk
• plant domestication, consumption of grains
• living indoors
• living in crowded urban environments