Darwin's theories were based upon observation, the are no rules in it. Darwin's work actually describes, contrary to what people assume, is that the fittest sp

Darwin's theories were based upon observation, the are no rules in it. Darwin's work actually describes, contrary to what people assume, is that the fittest species survives. Fittest doesn't mean strongest or healthiest, it in fact means its ability to adapt to the environment around it. Homo Sapiens as a species have adapted extremely well, we've moved from the Savanna and each new sub-species has spread further and further. In fact we went from living in a small region of Africa to spanning from the Arctic to Antarctic and from the most westerly point to the most easterly point on the map. In fact, humans are currently the only species to ever expand off the surface of the planet. Our survivability went from bipedal primates to astronauts, currently as a species we have the potential to survive possibly anything except a gamma-ray burst aimed in our direction. Warm blooded creatures won out over cold blooded creatures, despite wasting something like 32 times the energy. Why did this happen? Well aside from the apex predators, warm blooded creatures have decimated cold blooded creatures because we always have a constant supply of energy. Right now I can get up and go for a run, but then look at Crocodiles, they only have a range of a few feet out of their territory before they're not safe anymore. The Nile Crocodile is an awesome and fearful predator, but like all its cousins it only survives in one niche. They eat everything including all the big cats and baboons. However, even full adult Nile Crocodiles are easy prey once they're on land and even in water a troop of hungry baboons can get themselves some juicy crocodile by luring it onto land. My point is, the Nile Crocodile wins nearly every time in its territory, but it'll never win outside its territory. So what happens when the environment changes? Well migratory animals appear to shift their behaviors accordingly. The only hope for the Crocodiles is that it doesn't get too hot or too cold too fast, because unless the Crocs can spread through expansion they'll go extinct. When it comes down to individuals there's lots of things that contribute to whether or not you'll 'survive' and most are down to the individuals genetics. It doesn't matter if a person is strong or weak if they're physically incapable of procreation through infertility or any other means. Reproduction is downright genocide, the sperm are dumped into a hostile environment that's designed to kill them so only the strongest actually manage to get to the egg, then it takes several sperms to die before a single sperm can implant the egg (ironically the first to get there doesn't necessarily win) and then once the fetus is developing, the mothers immune system is on a war path to destroy it. If the child survives all that, then it has a good chance of reaching maturity and passing on its own genes. Simply saying that competition means one wins and one loses is absurd because individuals don't matter, it's the species as a whole and thats what Darwin was talking about. He didn't see a fist fight and say, I know I'm going to write the greatest thesis ever! No he traveled around the world and saw how wide spread and diverse species were and then he wrote the greatest thesis ever after seeing multiple sub-species spread throughout huge swathes of the earth. Cooperation between species is merely a subclass of competition in evolutionary terms. It usually occurs in two species of prey where they can share their abilities and as a pair they can compete and win against a predator. You seem to be thinking of the Clownfish/Anemone symbiosis. It's true that both benefit from this, however they're both competing for independent goals. The Clownfish helps prevent the Anemone from dying by cleaning it of undigested food, which can grow bacteria and kill the Anemone and in this manner the Anemone wins in competition against the bacteria/death. On the other hand the Clownfish is protected from predators by hiding in the anemone, which in turn means it beats its competition from any number of predators. This symbiosis doesn't thrive because cooperation is good, it thrives because the pair compete efficiently as a pair. However, if the symbiosis breaks down they both die.