Gaddafi Calls Ceasefire.

ninky_2

here you go gen. an explanation as to why self-limiting reproduction can give an evolutionary advantage...
http://necsi.edu/visual/pp.html


In this animation, predators' reproduction rates are indicated by their color: dark red predators reproduce infrequently, while brighter red predators reproduce more frequently. Notice what happens to very bright predators (that is, more selfish ones, using up resources more quickly). Although they reproduce rapidly, giving them an immediate advantage over slower-reproducing competitors, they soon wipe out all of the prey available to them. When no prey remain, these strains die out...........a new type of predator (shown as blue) is introduced. When a predator of this type becomes surrounded by other predators, it sends out a short-range signal. Other blue predators may respond to this signal by temporarily changing their reproduction rate. Again, the extent of this response may be slightly higher or lower in offspring than in their parents, due to mutation. And the response can be to reproduce either more or less frequently when the signal is present.
A traditional view, based on individual fitness, would predict that the successful evolutionary strategy should be to reproduce as quickly as possible in all circumstances. In contrast, what the model shows to be successful in the long term is to reduce reproduction when in the presence of the signal. Moreover, predators with this capacity for communication (blue) have an advantage over non-communicating predators (red).

ninky_2

more science behind the evolutionary benefits of self-limiting populations.

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WMD-4KDGTFH-B&_user=10&_coverDate=12%2F31%2F1975&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1687100067&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b87fcc40caf66337a152b6f75063d925&searchtype=a

This paper shows that Darwinian theory can explain the evolution of density governing limitation mechanisms which prevent overexploitation; they are a predictable by-product of selection for adaptation to the early growth phase of a population with recurrent population crashes. In this situation Darwinian selection, instead of maximizing the number of offspring of the ultimately favored allele, maximizes the number of its descendants in the comparable portion of the next growth cycle.

Generali

ninky wrote: »

here you go gen. an explanation as to why self-limiting reproduction can give an evolutionary advantage...
http://necsi.edu/visual/pp.html


In this animation, predators' reproduction rates are indicated by their color: dark red predators reproduce infrequently, while brighter red predators reproduce more frequently. Notice what happens to very bright predators (that is, more selfish ones, using up resources more quickly). Although they reproduce rapidly, giving them an immediate advantage over slower-reproducing competitors, they soon wipe out all of the prey available to them. When no prey remain, these strains die out...........a new type of predator (shown as blue) is introduced. When a predator of this type becomes surrounded by other predators, it sends out a short-range signal. Other blue predators may respond to this signal by temporarily changing their reproduction rate. Again, the extent of this response may be slightly higher or lower in offspring than in their parents, due to mutation. And the response can be to reproduce either more or less frequently when the signal is present.
A traditional view, based on individual fitness, would predict that the successful evolutionary strategy should be to reproduce as quickly as possible in all circumstances. In contrast, what the model shows to be successful in the long term is to reduce reproduction when in the presence of the signal. Moreover, predators with this capacity for communication (blue) have an advantage over non-communicating predators (red).

It's very interesting but as any good economist will tell you (not that there are many of those!) empirical evidence trumps modelling and I'm yet to be convinced that any species limits its reproduction in any meaningful way.

I guess as a sub-species, richer people could be said to as they seek to increase the success of their offspring in ways other than maximising their number. They are a fairly small sub-set of people as a whole however.

ninky_2

Generali wrote: »

It's very interesting but as any good economist will tell you (not that there are many of those!) empirical evidence trumps modelling and I'm yet to be convinced that any species limits its reproduction in any meaningful way.

I guess as a sub-species, richer people could be said to as they seek to increase the success of their offspring in ways other than maximising their number. They are a fairly small sub-set of people as a whole however.

:rotfl:i think even a top eugenicist would struggle to scientifically categorise rich people as a "sub-species".

mbga9pgf

No, I would categorise other social groups as that though.

Generali

ninky wrote: »

:rotfl:i think even a top eugenicist would struggle to scientifically categorise rich people as a "sub-species".

Ok, I was speaking tongue-in-cheek but at the same time, the people that are limiting their reproduction in a meaningful way are richer people.

ninky_2

Generali wrote: »

Right-ho.

Have we found any self-limiting species now? Elephants don't seem to be.

can't find the link for elephants just now. but here is one for rabbits and other rodent species.

http://www.answerbag.com/q_view/42724

Rabbits are capable of "freezing" the development of embryos for up to six months, at which point the pregnancy must either be allowed to continue development or aborted. In overcrowded and stressed conditions, rabbit females may hold onto suspended pregnancies that way for some time, to see if conditions ease and they have sufficient resources to sustain babies; however, if conditions don't ease, then the females will secrete a hormone mix which aborts the pregnancy and either resorbs the embryos for recycling of materials, or (if they are too far along in development) desiccates the embryos and then encysts them. A doe can carry up to 24 encysted embryos, with apparently no ill effects to herself.

Some rodents also have similar abilities to self-abort pregnancy under stressful conditions. However, another limiting factor of reproduction, in rodents and many other species, is predation of the young. In overcrowded and stressful conditions, many creatures will try to kill each others' babies (if nothing else, to try to give their own babies a better chance through lessening competition for scarce resources).

it could be argued that the activities we see around the globe in terms of war are a form of trying to kill each others babies over resource scarcity. i'd argue that self-limiting would be a better strategy.