“Genome: An Autobiography of a Species in 23 Chapters” is a delightful tour through the chromosomes in celebration of the completion of the human genome project in the early 2000’s. While all of the DNA had been sequenced, people knew only very little of it for what it actually does. This book proceeds to take one gene that we do know about each chromosome and tell a little story about it. Hence the 23 chapters.

Anyway, here are ten things that I learned from “Genome: An Autobiography of a Species in 23 Chapters”

1) Nordic people are more likely to be shy.

There was a study done correlating genes for shyness. It was found that children who tend to be shy also tend to be tall, pale, blue-eyed, and have a higher-than-average normal body temperature. That last part matters as in northern climes, having a higher core body temperature can be useful in avoiding hypothermia. As it turns out, one way to raise body temperature is to have the amygdala release a small amount of epinephrine (fight or flight) constantly. This activity in the amygdala appears to be responsible for both shyness and warmth.

2) Insulin -> Tryptophan -> Serotonin -> Melatonin. When it gets dark in winter, eat a cookie.

Funny way the body works. People tend to gain weight in winter. One of the reasons is that they’re more sedentary. Another is that the loss of light causes the brain to produce melatonin (the neurotransmitter that tells you to go to sleep) earlier. The easiest way to make melatonin is from serotonin, the compound in the brain for happiness, so the increased production of melatonin reduces the amount of serotonin in the brain, making you sad. Simple solution, the easiest way to make more serotonin is to use tryptophan, which your body gets when you raise your insulin levels. When you’re sad in the winter, yes sun lamps are good. Also try eating a cookie.

3) Kuru is partly genetic.

Turns out that applies to most diseases. What a surprise. For those don’t know, kuru is a brain disease caused by eating the flesh of someone who also has it. It is a neurodegenerative disease where a malformed version of the prion protein accumulates and causes damage in the brain and nervous system of the afflicted. It is a cousin of the mad cow disease.

4) 1% of our DNA is from Retroviruses.

Retroviruses are viruses that embed their dna into the host’s genome. At some point it made more sense to leave the DNA in there. This was considered to be a surprisingly large amount of DNA to be introduced by viruses.

5) A person with type AB blood is almost completely immune to cholera.

Resistance to diseases is the biggest advantage of blood types. I vaguely recall other blood type combinations being useful for other diseases, and the Africans have a recessive blood mutation that makes them resistant to malaria, with the trade-off being that many more are prone to sickle-cell anemia.

6) Some genes benefit one sex but harm another. This makes the X-Y chromosome separation desirable.

The book also goes into details about the X chromosomes lobbing DNA and attacking the Y chromosome. I didn’t exactly follow that part, nonetheless, the Y chromosome is shrinking. In a few million years, we may not have a Y chromosome. I personally am quite afraid of losing my own Y chromosome in a million years. That would be tragic.

7) Placental genes come from the father but genes affecting brain development are from the mother in rats.

This seems to be a defence against promiscuity, in the sense that when a mother has multiple pups from different fathers, they will end up competing for resources. Evidently, there are some genes that enhance viability in the placenta, giving that pup the chance to crowd out its half-siblings. Brain development requires developing more slowly, so the incentives for the mother and father are genetically reversed. As a result, the fast-growing placental genes are selected for by the father, whereas the genes affecting slowing down and developing brains comes from the mother.

8) Lots of DNA exists as a parasite on its host genome.

There’s no simple way for the body to remove DNA from it’s genome when it stops doing something. And over 95% (perhaps 98%) of DNA does not code for proteins. This was initially labelled as ‘junk DNA’ (which corresponds i think to when the book was written. Later on, it was found out that some of that “junk” DNA plays a vital role in the regulation of other DNA, or codes for RNA that has a function specifically as RNA. However, i’m sure a bunch of it remains junk.

9) It is less deadly to have an extra copy of a smaller chromosome.

Someone with two copies of the smallest chromosome (not counting the X and Y) has down’s syndrome. A fertilized egg with three copies of the largest chromosome will die within ten days of conception. Have two copies of a chromosome slightly larger than the smallest, will not survive infancy if it’s one of the few lucky enough to make it that far.

10) Arthropods have nerve columns on their bellies; one of our mutual ancestors was upside-down.

Was it us? Was it them? Flip over!

Have a great week!

-Michael