Lecture 13 - Theories Of Aging

Question 1

Why do we not bother biologically explaining ageing? What do we try and explain instead?

Answer 1

Everything ages, it’s natural and inevitable. Therefore we try and explain why certain things don’t age or more precisely why things can delay ageing.

Question 2

Over the life span what happens to an organism?

Answer 2

Damage accumulates which leads to reduced functionality and therefore reduced fitness.
An organism can detect and repair damage but it’s not 100% effective

Question 3

Why aren’t repair mechanisms not 100% effective?

Answer 3

The repair mechanisms age as well and become less functional

Question 4

So there is damage that is caused by outside forces that can be detected and repaired. What’s another kind of damage? Eg cancer

Answer 4

Cancer is parasitic genetic damage that not only causes a loss of function but also exploits the organism. Therefore, it actively kills that organism and steals their resources

Question 5

What category does cancer fall in? Medical term

Answer 5

Malignant neoplasms

Question 6

Define cachexia

Answer 6

Wasting away due to cancer stealing your resources like energy.

Question 7

So why might neoplasms not be detected and eliminated like other kinds of damage?

Answer 7

Although some neoplasms are detected by the immune system . Sometimes the problem is the immune system. Diseases like lymphoma and leukaemia are both examples of when the immune system becomes malignant.

Question 8

In terms of natural selection and human lifespan, why can’t we live forever?

Answer 8

Natural selection aims to improve reproductive success, it does not work to optimise lifespan.
Any organism that favoured lifespan over reproductive success would be out competed and extinct by other organisms that favoured reproductive success and had more offspring.

Question 9

How can males increase their lifespan?

Answer 9

Increase it by becoming eunuchs, through castration. Reduces the harmful effect of make sex hormones

Question 10

What is the cost of longevity?

Answer 10

Everything has to be made more robust and to last. All of hat takes away from the here and now reproduction.
Investing in eggs and sperm, caring for offspring, number of offspring

Question 11

So why do humans live to the age we do?

Answer 11

We are built to last the optimum reproductive level, with a little extra so we can care for offspring

Question 12

How can we tell that most of our body is built to last to this set age of approx 70 years?

Answer 12

Elderly people once they hit a certain age tend to have multi system organ failure as all their organs wear out together.

Question 13

Why are humans some of the longest lived animals? Why is it necessary?

Answer 13

Each human child takes a while to reach independence and sexual maturity. They need parental investment like feeding, shelter, defence, teaching and help with mating.

Question 14

What’s the minimum age evolution would have a human live to?

Answer 14

Minimum would be about 45-50, because you need to have about 6 children spaced 3-4 years apart. Then you add a little more to about 70 years so you can help each child in maturation.

Question 15

What was the max lifespan in hunter gatherer society?

Answer 15

70 years

Question 16

In the brain where are you most likely to get cancer?

Answer 16

In the glial cells, as they are the only ones to divide and therefore mutate. Nerve cells and muscle cells don’t divide and therefore won’t mutate.

Question 17

What aspects of human psychology change with age?

Answer 17

Memory
Intelligence
Personality

Question 18

What 4 other ways can old people’s brains change as they get older?

Answer 18

1) increasing proportion of dementia
2) brain is effected by physical disease, like lung disease leads to decreased oxygen to the brain
3) increased prevalence of psychological disorders eg depression
4) effects of prescribed drugs and polypharmacy - drugs like statins effect b.p. And brain impairing effects

Question 19

How dies entropy relate to ageing?

Answer 19

Everything loses structure, everything ages and therefore loses structure.