Why do octopuses commit suicide after mating ?

It's a little-known fact, but the octopus is extremely intelligent : it has extraordinary cognitive abilities thanks to its large nervous system and large brain-to-body mass ratio. However, it does not live that long because of an amazing phenomenon, but no less common in this species : suicide after mating.

The octopus has a hard time mating

If it is able to fool its world, by imitating other animals, by handling tools, by making its own tentacles grow back when they are cut, the octopus does not use its intellectual capacities to ensure a long life. The octopus only lives for one year on average.

The reason is simple : after its first mating, which generally occurs after a year, this cephalopod lets itself die. After laying its eggs, the female octopus begins a fasting process and self-harms. it retains most of its strength until its eggs hatch, then simply lets itself die due to its degraded state of health.

The male octopus also has difficulty surviving life as a couple. When they reach one or one and a half years of age, they tend to stop feeding and die just after their females.

This self-destructive behavior of the octopus is explained by a change in its cholesterol metabolism, induced by its optic gland. This is a new study produced by the universities of Washington and Illinois, which has updated the functioning of this "programmed death". This gland, whose equivalent in vertebrates is the pituitary gland, produces, after mating, steroid hormones, which drive the female to suicide.

The role of cholesterol in suicidal behavior

The novelty of this study lies in the discovery of the role of cholesterol in self-destructive behavior : in 1977, scientists had already understood that the optic gland was the cause of suicide in octopuses, but had not found what induces this behavior.

This time around, the researchers figured out that when the octopuses went fast after mating, there were higher levels of activity in the genes that metabolize cholesterol. This is also known to play a fairly important role in animals, especially in the production of stress hormones.

But this phenomenon could explain certain behaviors in humans. There is a genetic disease, Smith-Lemli-Opitz syndrome, caused by a mutation in the 7-DHC cholesterol gene. Children affected by this syndrome, like the octopus, would have suicidal behavior and tendencies to self-mutilation.

Humans still have a lot to learn from the octopus...