Theory of Evolution is a comprehensive body of knowledge that explains how all life has originated from a single source. How it branched out into myriads of different lifeforms we have now as well as how each of these lifeforms have evolved to better adapt to their chosen environment.
The example in the picture is how giraffes gradually evolved to have longer and longer necks. Why longer neck is an advantage, a simple fact that it allows giraffe to eat leaves that grow higher and higher on trees, leaves that are inaccessible to other shorter animals. The fact that these leaves are inaccessible to shorter animals gives giraffe a clear competitive advantage, instead of competing with smaller animals for the scarce vegetation that grows on the ground level, giraffes figured how to get taller and access leaves that are too high for others to reach. Thanks to that giraffes have access to more food than others and could just chill as they munch on high crone leaves as their shorter brethren like zebras and buffalos are roaming around in herds in search for grass that was not eaten yet.
This is but one facet of evolution, but it does a great job illustrating not only how it happened but also why it happened. Not every change and branch of evolution was conditioned by attempt to gain advantage over other species, but most influential ones certainly did. Including the one branch that leads us to us, humans. We top by far the most shrewd and industrious branch that never failed to explore new ways of doing things to gain an advantage over competitors (other species).
It begun already in the ocean, or much rather river, when we were still fully aquatic species, known as fish.
I want to clarify that we did not branch out of cod, tuna or sardine. These species of fish choose an evolutionary strategy that is polar opposite of ours. They chose to constantly adapt to existing environment and survive. That gradually made them smaller and dumber but nimbler, more slippery and hard to catch. They now live their lives in large herds (schools of fish) because if predators attack them, there are greater chance they will eat a few and the rest will escape. You might say they constantly sacrificing a few members of their species so that the rest may live.
This evolutionary strategy gradually shaped them into distinctive oval fishy shape. Early fish were all sorts of shapes, but generations of evolution perfected this typical for fish shape and coalescented them into species we know today and use for making fish and chips.
That is not something that happened to our ancestors, they either retained or perhaps gained a rather distinct rather non-fishy look and shape. Catfish or Sturgeon are good example of that. Look at them carefully, they are soft of middle ground between, fish, lizard and a snake. Something that could gradually become either of these species. Wider head allows for a bigger brain and a more quadruplectic shape allows for forays onto the surface.
Thanks to their bigger brains, our ancestors figured out how to hide from predators in places they will either not look or not be able to fit, the rivers. Ocean is big and there are plenty of space for sharks, orcas and other predatorial fish. In contrast river is narrow, a shark will have a hard time fitting in and navigating something like that. Hunting in such environment will be too hard to an aquatic predator.
That was a defence advantage for our ancestors. Slow and easy to catch due to suboptimal shape, they would be easy prey in open ocean. In the river however they were safe. Here they were not a prey for bigger fish but a big fish in a small pound instead. A clear advantage that their fish brains managed to figure out and take advantage of. Something their oceanic brethren could not. In rivers they were safe. food was more plentiful and they could chill, take it slow, eat plenty grow bigger and smarter and think of the next move that will take them even greater.
New environment also changed what our ancestral fish looked like. It was not an endless space of water, like in the ocean but a limited space between surface and riverbed. To live in this area our ancestors had to adapt to handle these diverse conditions. Every so often they might even accidently get pushed either to surface or shallow banks of the river. Being able to get back to water would be essential in such situation. Moon cycles also mean water level changes based on time of day. What was submerged can become exposed and later resubmerge again.
Navigating this new environment meant our ancestors bodies has to be not specialised to one environment like for pelagic fish but be flexible and be able to not only swim but also crawl and more. We already originated from demersal fish that lives on the bottom of the ocean and traits that distinguish demersal fish from pelagic one only further exacerbated in rivers. Unlike heavily specialised pelagic fish, our ancestors became true jacks of all trades. All these traits allowed them to make "one small step for a fish, a gigantic step for Fishkind", advance onto the surface. Later on, Neil Armstrong did the same for humanity.
Rivers were all good and dandy, but gradually they have become overcrowded too. Food was no longer enough to feed everyone; Barracudas preyed on smaller fish and particularly on newly hatched baby fishes who still have not grown to defend themselves.
As the same time solution all our ancestors' problems lie right above the water line, the surface. There was plenty of food, no predators and plenty of space. If only they could just live on the surface, they would be kings.
The problem was the same as for humans in space: breathing. Fish could not breathe on the surface. Was that a dead end then? Now we of course know it was not, but for our ancestors it was quite a problem.
However, if one could nor breath on the surface, what if you hold your breath, briefly jump out to grab a bite and then swiftly get back before you run out of oxygen. I am pretty much certain that our ancestors lived like that for quite some time. Those who could stay on surface longer could therefore eat more, get bigger and stronger and have better chances to breed and pass on these traits to next generation.
Eventually however a fortunate mutation evolves one of them a lung and allowed them to actually breathe on surface without getting back. Australian and several other species of lungfish still live out there.
First fish with lungs certainly ate plenty during its unlimited stay on the surface and return to river to breed as a ginormous by fish standards giga Chad who definitely, put lungless fish out of dating market. Soon there were many more lungfishes roaming around the surface and eating completely helpless and defenceless insects and more.
Gradually even surface around rivers and lakes became overcrowded. Further evolution gradually changed these lungfish into myriads of different amphibians, like frogs or newts. Eventually we managed to break our dependence on rivers, but early surface species could not. Adult species could live on the surface for prolonged periods of time, but their infants could not. Thus, to breed, they had to go back to water.
Amphibians like frogs look anything like fish from which they originated, yet they have a clear connection to them. Frogs lay their eggs in water and tadpoles that hatch out of them look much like infant fish of any other species of fish, they do not have limbs and cannot live on the surface like their parents. Only as they grow older, tadpoles gradually develop limbs together with ability to live on the surface. Eventually they leave their ancestral home and live on the surface in adulthood.
Reptiles that evolve out of amphibians do not have this problem. They can lay eggs on the surface and juveniles that hatch out of eggs are surface ready. Formative years, that amphibians spend in water, are spent inside egg instead.
In humans and other mammals this instead happen inside womb of a woman. Early human embryos look much like a tadpole with no arms and legs, before they gradually develop limbs and other human like features.
This is but one example, but in every other stage of evolution we always took the smartest and most ingenious solutions to our problems. When surface became too crowded, we evolved into living on trees, like lemurs and monkeys still do nowadays. When trees became too crowded, we learned to hunt mammoth and other such huge animals. When we ran out of mammoth to hunt, we learned to grow crops, husband animals, build things and now we have power, an average fish could not even dream of. By now most of our former brethren are but helpless primitive beasts for us to hunt or breed for food or sport.
Thus, our destiny is not in adapting to survive on this ever-shrinking overcrowded planet, but to go beyond and reach the stars. Space is ours for the taking. We do not need this planet or even staying human. Why be human when we can be something much greater. Lungfish did not think of staying fish when it managed to reach the surface, it thought of opportunities the surface life brings. If we fail to do the same, all the lungfish in the world and all the monkeys in the world will laugh at as.
Religions such as Christianity is the way of the sardine; science is the way of lungfish. The latter will make as an Ubermench, a human beyond humans, a being that will transcend humans, the former will make us a future canned food for the latter. I do not think it's a hard choice to make.


