Evolution: Do organisms really adapt?

Two important things must be remembered when we are talking about evolution. People often talk as if it’s very quick. That leads to stupid questions such as, “why do I never see a monkey giving birth to a human”. If that happened evolution wouldn’t. Offspring resemble their parents. If they didn’t they’d be killed and thus evolution wouldn’t start.

Evolutionary changes are gradual. Even if an individual was ever so slightly better adapted to its environment than its parents there’d be no noticeable difference. You couldn’t go to the African savannah and say look at that juvenile leopard its far better adapted than its mother. You’d see no difference.

This is where many young Earth creationists argue it can’t have happened because there hasn’t been enough time for evolution because it is so slow. Their problem is they’re wrong. There has been enough time. There has been four and a half thousand million (USA: billion) years for this to happen. That can be expressed as 4 500 000 000 or 4.5 x 10^9. It’s an incredibly long time. We’re used to dealing with the historical timescale of about 10 000 years. Even one millennium (1000 years) seems a long time ago to us. The timescale available for evolution is 4 500 000 longer than one millennium. It’s a colossal amount of time.

Evolution does happen. It happens as the result of small, gradual changes. That requires a lot of time and evolution has had a lot of time.

adaptation can be used in different ways, it can be used as a range of physiological responses (e.g. your hemoglobin level will change if you move to high altitudes which is your bodies adaptation to living at high altitudes) to adaptation at a species level where individuals with certain traits have a higher survival chance, but the trait does not and cannot change over the lifetime of the individual. It changes only if you look at the traits incidence in the population.

Whether you have a difficult time believing anything only has a bearing on a subject if you are thoroughly familiar with a subject. I don't know how old you are and how much background you have in biology, but I would suggest to get a good textbook about evolution from a library and study it if you want a lot more detail.

Based on your question you need quite a bit of additional background, and it is not possible in this forum to cover all the material you might or might not need in order to understand evolution. Reading through a book or taking a biology class where you get through the material over weeks would be the best for you.

There is no doubt whatsoever that gene frequencies in populations change over time, which is pretty much what adaptation of populations means.

All species are adapted to their particular niches. We are no different. We walk on two legs because it is an adaptation to our environment, namely the open African savanna, where our ape ancestor evolved bipedalism. Our ancestor was a quadrupedal ape, and they had to walk on 2 legs even though their bodies were actually adapted to walking on all 4 legs. Once they started walking on 2 legs, any mutations that make them better 2 legged walkers would also make them worse 4 legged walkers. That did not matter because they weren't walking on 4 legs, so these mutations were incorporated into their genome. OTOH, if the same mutations were to happen to an ape, then they would be eliminated since an ape that does not walk or run well on 4 legs is not adapted well to its environment. Therefore it is adaptations that can change the course of evolution and the biology of organisms. Yes, adaptations are not only real, they are also necessities. Animals and plants that did not adapt are part of the fossil record of extinct organisms. To be fair, some organisms are extinct because of catastrophes like mass extinction events, even though they are well adapted to their environment.

Take for example the Desert pupfish of Death Valley, California. They are adapted to hot temperatures, temperature that are hot enough to kill most fish. Yet more then 13,000 years ago, Death Valley was a glacial lake with cold water temperatures because it was an ice age. After the ice age ended, the lake began to lose water, and now there is no lake over there, only small isolated pools. The ancestor of the Desert pupfish was not adapted to these small pools but to a large glacial lake but a changed environment makes it necessary for the descendants of this glacial lake species to adapt to new hotter conditions or become extinct.

First of all adaptation of an individual to a change in conditions is not evolution. Individuals do not evolve. Evolution happens in populations over generations. An individual human who moves to a higher altitude may adapt to the changes in pressure and oxygen levels, but that's not evolving.

Evolution is when a population living in a higher altitude has more offspring that have traits that favor high altitude, such as higher lung capacity, or more efficient hemoglobin. Those offspring that don't have such traits are out competed for resources by those who are better suited. Over many generations the populations will be more likely to have more individuals who have traits that are suited for that altitude.

Its not a conscious thing. Read about the difference between short distance and long distance runners, and the geographical locations that tend to produce the most. There is a cultural and biological advantage to running there