Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: thedoc on 05/10/2012 03:30:01
-
Elizabeth Johnson asked the Naked Scientists:
Hi, my name is Shannon.
I've got a quick biology question.
Where did survival instincts (or any instincts, for that matter) come from? It seems to me that Darwinism revolves around an organism's will to live, but how did that will to live come to be in the first place? I expect there is a simple answer, but I cannot seem to find it. I have an incredibly hard time imagining how the will to live can be reduced to a configuration of matter.
Considering how essential this concept appears to be in understanding the evolution of life, I am slightly concerned, and would greatly appreciate any feedback. Thanks!
Sincerely,
Shannon
What do you think?
-
Those animals that don't have "survival instincts", finding & eating good food, avoiding predators, etc... have a greater chance of dying. And, thus less likelihood of passing on their genes.
Those that are more effective in surviving to reproductive age have a greater chance of passing on their genes.
Keep in mind that survival instincts may be different in different species. Salmon, for example, survive tremendous hardships to arrive at their spawning grounds, then die.
Praying Mantis Males may make the ultimate sacrifice to feed their mates. Likewise, there is a reason why one never hears about black widowers.
-
Humans and animals have survival instincts. Where did that came from?
-
an organism's will to live
The way the question is phrased might suggest that "will to live" is a "conscious intent".
However, the biological imperative to "reproduce or die" is apparent in bacteria and yeasts which noone seriously suggests have a conscious thought life.
It is even apparent in viruses which don't even meet the basic criteria for being alive.
"reproduce or die" is a technical hurdle which man-made machines are yet to approach (outside of computer "viruses", Terminator movies, and such-like). A bit scary to contemplate...
-
It's amazing enough to know that molecules that can replicate themselves exist. If a particular type of molecule not only can but also takes active steps to do so then it will persist. I imagine there were many self-replicating molecules approaching the complexity of DNA that only survived a generation. However, the degree of chemical complexity necessary to go from "can replicate" to "replicate!" seems trivial in comparison to the origin of self-replicating molecules themselves.
If one thinks of the millions of DNA-type molecules that would have been created in the universe its not hard to think that some of them might contain "programming" to actively replicate. After all, we used programmed molecules all the time, soap being the most obvious example.
I think the instinct to survive is adequately explained by science.
-
A breeding population will naturally produce a distribution of behaviours; a majority of the population will be between the extremes of any particular genetically determined behavioural trait. In a population of mice, for example, there will be a few big risk-takers and some very risk-averse members, with the majority distributed between the two extremes.
In good times, with few predators, the risk-takers may have a wider foraging range and be more successful than the rest, producing more and healthier offspring. Over time, this will skew the population towards risk-taking as more of them will have the risk-taker inheritance. In dangerous times, with lots of predators, the risk-takers don't survive long, and it's the risk-averse that do better than average, surviving to have more offspring, and so eventually skewing the population towards risk-averse behaviour.
There will still be a variation of behaviours in each generation, from risk-takers to risk-averse, but the population average will move one way or the other due to selection.
In a more risk-averse population, there might be some that tend to freeze in the face of a possible threat, and some that tend to run away. The ones that freeze will do badly if the predators are snakes, and the ones that run away will do badly if the predators are birds. This will be reflected over time in the behaviour of the population as a whole. So it is the nature of the selection that determines what 'survival instinct' behaviour is most apparent in the population.