R27 human evolution

Question 1

What family is Humans in ?

Answer 1

Humans family is called Hominidae (contains gorillas, humans, chimpanzees and orangutans)

Question 2

What genus are humans in ?

Answer 2

homo

Question 3

What is the subgroup of hominidae ?

Answer 3

homininae doesn’t include pongo (orangutan) diverted 12 million years ago

Question 4

What are the 3 species of homo 40,000 years ago ?

Answer 4

the homo sapien, homo denisova and homo neanderthalensis

Question 5

What are the homo neanderthalensis ?

Answer 5

Homo neanderthalensis lived 70,000 – 20,000 years ago, found in Europe and asia
- Same average height as pre-industrial humans but with larger brains
- Shared genes with humans (non-sub-saharan africans)

Question 6

What are the homo denisova ?

Answer 6

Homo denisova diverged 600,000 years ago from the neandertals. Overlapping land areas with the neandertals
- They are introgression with humans like Melanesians
- Genetic evidence of inttrogression with neandertals and denisovans

Question 7

What was the MRCA for the 3 homo species ?

Answer 7

The ancestor for the 3 homo species was the homo erectus. The three species descended from intogression between species. There is some theory that these 3 species are subspecies.
- Evolved in Africa 2 million years ago and left 1.9 million years ago
- Used stone tools and possibly the first to use fire
- Extinct by 200,000 years ago

Question 8

What are some past selection pressures on humans ?

Answer 8

• Diet (starch, lactose)
• Local climate (elevation)
• Pathogen resistance (malaria)

Question 9

What are some present selection pressures on humans ?

Answer 9

• Diet(cholesterol)
• Pathogen resistance (malaria, HIV)
  medicine (baby head size increase)

Question 10

What does evolution require ?

Answer 10

• Heritable variation and one end of the extreme needs to benefit survival and reproduction.

Question 11

What diseases has evolutionary medicines helped cure ?

Answer 11

• Haemophilia A
• HIV (CCR5 delta32 allele)
• Hereditary blindness
• Parkinson’s disease
• Leukaemia

Question 12

What was the outcome to humans and neandertals introgression ?

Answer 12

• Produces receptors in white blood cells, HIV binds in order to infect. Homozygous people do not make the receptors so are immune from HIV.
• This is an example of antagonistic pleiotropy

Question 13

What is genetic engineering and why is it difficult ?

Answer 13

Genetic engineering: the potential to change any DNA sequence before fertilisation
- It’s difficult due to complex development and other factors like epistasis, pleiotropy and the environment

Question 14

How can we tell evolution is happening in humans ?

Answer 14

• Compare allele frequencies of two or more populations
• Compare fitness with allele frequencies of different populations
• Evolution of humans was entirely down to the world being a diverse environment
  o Some areas are marine, cold, lactose diet, malaria present, elevated

Question 15

Is natural selection acting on humans and how can we tell ?

Answer 15

• There is still genetic and phenotypic variation
• There is still heritable variation
• There is probably a fitness difference between individuals