Meaning, does evolution occur with a purpose? I understand that there is no true purpose as to why evolution takes place, but, to my knowledge, it can be labeled as a process. For example, the panda bear with the “thumb” (a.k.a. the sesamoid bone). Would the panda acquire that trait that would cause the bone to evolve if he had not migrated away from his original niche? The environment does stem to the members of the species adapting some physical traits, but their offspring will not automatically be born with those traits. Thus, what I am essentially asking is does evolution occur for a reason? Does variation play a significant role since without variation, all species members of a species would be the same and if they were all identical and they shared traits selected for, then that would cause that group of species to disappear? Therefore, evolution occurs to prevent extinction? Am I right? I know this is kind of confusing, but some please, please help me!!
It happens out of necessity to preserve the species in a changing environment. Look at the English Pepper Moth; during the industrial revolution the soot from factories covered white barked trees turning them dark grey. White moths were easy prey as they were easy for birds to see on the black tree bark. As a result black moths reproduced more and completely changed the main color of the moth.
Short answer: no
It’s a good question, and was actually one of the early debates in the scientific history of evolution — does the need create the mutation, or does the mutation suit the need? Giraffes eat the leaves at the top of trees — do they grow long necks to get at the trees, or do the ones with long necks just happen to do better and out breed/outcompete the others? It’s the latter.
What you described (the first theory) is called Lamarkean evolution, named after the early 19th century biologist who championed the idea.
A variation of this question – is evolution adaptive? – has been simmering for about a century. Darwinian theory says no, that changes take place with no regard to adaptation and that die-off occurs more rapidly in less suited (adapted) variants. More recently Gould and Vrba suggested adaptation was not the point, exaptation (being fit for life wherever the organism was) was the point. The concept of orthogenesis, evolution with direction, was tossed around in the 19th century and widely decried for being Creationism. The perennial terror held in many evolutionary circles for intelligent design was voiced in Julian Huxley’s landmark 1942 book, Evolution: the Modern Synthesis, in which he noted some of his flock still decried adaption for “its alleged teleological flavour.” Even today we can see evidence of rectilinearity – the continuation of a modification (like our large brains) beyond the useful point. Modern microbiology says how that can happen (transposons can carry copies of partially dominant genes to multiple loci) but for a century or more talking about rectilinearity was enough to get you labeled a religious nut. Science, indeed.
For all that theoretical talk, *everybody* still talks about adaptation being central to evolution. When I was taking a train tour of the Phoenix zoo (any shady seat is bliss at the Phoenix zoo) the trained guide was talking about how the baboons could sit on hot rocks because they had adapted to it by developing ischial callosities on their buttocks. Calling Mssr. Lamarck!
Evolution is a change in the gene frequency in populations over time. The reason gene frequencies change is natural selection – the differential reproductive success of individuals based on variation in their phenotypes. The result is a population well-tuned for their local environment – if the environment changes significantly, a whole new set of selective pressures come into play and gene frequencies experience more significant change. There is no final evolutionary state or forward thinking involved, if the genetic variation of a population can not cope with environmental change, the population dies, if all the populations of a particular species die, the species is extinct. 95% of all species that have ever existed are now extinct.
Evolution is better defined as a pattern, not an actual process. The “process” that drives evolution is mutation. Mutations occur constantly and randomly. Those that confer some advantage (or no fatal disadvantage) endure from generation to generation and tend to become more dominant within the population of that organism over time and over changes in ecological pressures. Those organisms with mutations that are disadvantageous will tend to die out within the population. It is simply an extremely long timeline of random changes and “luck of the draw” survival. There is no purposefulness in it, at all.
“A zygote is a gamete’s way of producing more gametes. This may be the purpose of the universe.”
Robert Heinlein (1907 – 1988)
In other words evolution doesn’t have a planned direction or an end product. However it does respond to the environment the organism deals with. In short we didn’t evolve wings because there was no environmental need to do so.
Most evolutionary change helps the individual survive long enough to reproduce. That’s the true meaning of “survival of the fittest”