Chapter 14: Immortality (Genome)

•The genome is immortal, meaning it can be passed down through generations with no breaks or fatal mistakes.

• However, becoming an ancestor is difficult, and natural selection requires it to be difficult.

• If the human race does not survive (most species last only about 10 million years), none of us alive today will contribute anything genetic to the future.

• The reason the body dies while the genome remains immortal is because of something called telomerase. Telomerase is a protein that causes senescence (the deterioration of cells and tissues with age).

•Telomeres are the endcaps of chromosomes that protect them from deterioration.

• Over time, telomeres fray and shorten with each cell division.

• The presence of telomerase, an enzyme that rebuilds telomeres, is what prevents genes from being left off in egg and sperm cells (the direct ancestors of the next generation).

• Telomerase has been around since the dawn of life and uses almost the same RNA template in all descendants. However, ciliates (a type of protozoan) have a different phrase repeated in their telomeres.

• The complete telomerase machine has only been isolated in ciliates; human beings have not yet been able to identify all proteins involved in making human telomerase.

•Brain cells do not replace themselves, but glial cells (support cells) do duplicate themselves.

• Telomeres on brain cells probably shorten with age, but this is not the main cause of aging.

• Cancer, muscle weakness, tendon stiffness, hair greyness and changes in skin elasticity are not caused by cell duplication.

• There are big differences between species in how quickly they age.

• Animals have a similar number of heartbeats per lifetime when measured proportionally.

• Bats and birds live longer than expected based on their size and heartbeat rate.

•Steven Austad’s study on the island of Sapelo reveals that Virginia opossums age more slowly than their mainland counterparts.

• This is due to natural selection for better health after two years of age.

• Human beings are large, well protected by weaponry, and have few natural predators, so they age slowly.

• Natural selection has built our telomeres of such a length that they can survive at most seventy-five to ninety years of wear, tear and repair.

•Ageing is controlled by many genes, with estimates suggesting there could be up to 7,000 age-influencing genes.

• Ageing is the deterioration of many different bodily systems simultaneously.

• Genes that determine the function of any of these systems can cause ageing.

• Immortal cell lines often used in laboratory settings are derived from cancer patients.

• Cancer rates rise steadily with age and almost any human gene can accumulate mutations which cause deterioration after breeding age.

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Related posts:

1. Law 17: Seize the Historical Moment (The Laws of Human Nature)
2. Part 2: Isolate the Victim (The Art of Seduction)
3. Chapter 16: The Capitalist Creed (Sapiens)
4. On Nietzsche’s Thus Spoke Zarathustra Summary (8.4/10)