Philosophy Now Forum

What if the reason why there's so much convergence between species in their design, is not just because the same genetic mutation is bound to occur in two different species, and spcies inhabit similar environments, requiring similar traits to survive, but also because genes themselves and the way cells are fundamentally structured, means only so many traits can be produced? What if the number of traits species can evolve is limited, limited by the nature of genes and cells themselves, by the fact they're structured a certain way, and there's only so many ways you can rearrange them? What if there's trillions, or even an infinite number of (in)conceivable behaviors and morphologies that can never be expressed by cells and genes because of their inherent limitations? For all we know, life, or something like it, in other parts of the universe, may comprise things other than cells and genes, or may comprise cells and genes, but different sorts of cells and genes than we're used to, and as a result, life may appear and behave in ways that're radically different to the ways life on earth appear and behave.

We typically hear evolutionists say - if this or that trait evolved, it's because it offered this or that species a survival advantage, but what some of them forget is, mutations occur for no reason, or the same reason todays Iliad and Odyssey is not identical to yesterdays. The genome is constantly being rearranged, occasionally, rarely for the better, usually for the worse. For example, a species may have such and such trait, let's call it x trait. X trait is a very good trait to have, but a mutation occurs in one or several individuals, let's call it y trait. Y trait is superior, and overtime, it gradually begins to supersede x trait, because individuals with y trait tend to preserve and propagate themselves 10 times more than individuals with x trait. However, another mutation occurred in these individuals with y trait, let's call it z trait. Z trait is a more/less useless trait, in that it doesn't offer a survival advantage. It even hinders the species survival a little, but because y trait is so useful, z trait, which happened to evolve alongside it, gets preserved and propagated. Slowly, the species changes, it becomes superior to what it once was, relatively speaking, it can survive in its environment, which has remained largely unchanged, a little better. Overall, it's superior, because of y trait, however, z trait is useless, but it's managed to multiply itself in spite of its uselessness.

A problem for evolution, in my mind at least - let's say a species is on the verge of extinction. It was once 1000000 individuals strong, it's been reduced to 10000 individuals weak, by its rapidly changing environment. X mutation happens to occur in one of these individuals. X mutation is critical for the species survival. Problem is, it only occurred in one individual, the odds of it occurring in all the others simultaneously, is next to nil. How does x individual with x mutation, propagate himself and his mutation, since whenever he breeds with another individual, some of what makes him, him, that is to say, unique, is lost? I guess it could be 50/50, A or B rather than A/B or B/A, in some cases x mutation survives conception, in other cases it doesn't. In the cases it does, the offspring tends to survive, in the cases it doesn't, the offspring tends to die. I suppose it's not a problem, I figured it out myself.

The relevance of ancient literary works to evolution eludes me, unless you mean to compare printed copies to chromosome replication. If so, I don't believe biologists do "tend to forget" random mutation (or errors in replication); I think they're very much aware, not only of the randomness of, and imperfections introduced by, mutation, and also of the statistical prevalence and cumulative effect of each.

As for species becoming progressively 'worse' because of coincidentally co-transmitting genetic traits, I suppose that would be a matter of perspective. I suspect the insanity gene we modern hominids all have came down from Cro-Magnon, along with his high energy and inventiveness.

So, what did you want to discuss?

If a trait evolves that is beneficial it will likely promote sexual fitness meaning a particular animal way live to breed for a longer span than previous ancestors, in turn meaning it will become more common. If it is detrimental it will do the opposite, all that means is over time mutation produces many random codings, some like cancer are not beneficial but a consequence of gene expression, cancer is not a mutation per se, it is what genes do when they are forming the embryo stages of life, it merely becomes a problem when it happens outside of the womb and tissue begins to grow where and when it is not meant to. So essentially beneficial traits or at least not detrimental ones will stay in the gene pool, hence still remain in the organism, some like stronger limbs clearly benefit say tree dwellers and feet that can grip like hands. It's not random evolution despite what some people think mutation is random natural selection is not, it is unpredictable yes, but it is merely chaotic not truly random although of course there are natural laws which dictate how fast mutations can happen and if they will due to exposure to toxins, birth defects etc.

Certain traits crop up over and over again over time simply because of Earth's ecosystem and geology, how it is set up and this in turn might lead you to the conclusions there is some sort of rule to mutation, this is not the case though as Dawkin's said the watchmaker is blind, some watches he keeps, some he throws away. Although some watches are often found again later on despite being poorly designed at that time.

The whole thing keeps on ticking, for example sickle cell anemia causes premature death and occurs most often in sub Saharan Africa, this is no accident it just so happens the thalasaemia major aka sickle cell anaemia is very harmful, but thalasemia minor which occurs when only one parent has the mutation conveys immunity to malarial parasites because the parasite has trouble penetrating the odd shaped red blood cells. Hence even something seemingly detrimental might have positive evolutionary benefits, it's some times hard to tell.

"It is not the strongest or the fittest that survive, it is merely those most able to adapt."

Charles Darwin.

99.9% of all species on Earth went extinct that should tell you something. Evolution is blind, it is simply a process that produces mutation, epigenetics studies how the environment can produce them for example. But it's a feedback loop between the two prime movers, mutation and environment or natural selection. On the whole there is a tendency to evolve better adaptations by gradual accumulation, but this is by no means sure to make your survival certain, mother nature is a fickle bitch.

People place human values on something that is arbitrary and has no regard for survival or indeed the consequences of its development, or anything else, in that sense the Watchmaker is both blind and brainless.

I like to think of evolution like a zombie, it is persistently vegetative, tenacious and it will not stop shambling on, without a shotgun blast or two, and its only master is not some necromancer but the randomness of it's source code and the natural laws there in.

Current research findings and examples of effects

Epigenetic changes have been observed to occur in response to environmental exposure—for example, mice given some dietary supplements have epigenetic changes affecting expression of the agouti gene, which affects their fur color, weight, and propensity to develop cancer.[90][91]

One study indicates that traumatic experiences can produce fearful memories which are passed to future generations via epigenetics. A study carried out on mice in 2013 found that mice could produce offspring which had an aversion to certain items which had been the source of negative experiences for their ancestors.[92][93] Reports stated that:

For the study, author Brian Dias and co-author Kerry Ressler trained mice, using foot shocks, to fear an odour that resembles cherry blossoms. Later, they tested the extent to which the animals' offspring startled when exposed to the same smell. The younger generation had not even been conceived when their fathers underwent the training, and had never smelt the odour before the experiment.

The offspring of trained mice were "able to detect and respond to far less amounts of odour... suggesting they are more sensitive" to it, Ressler told AFP of the findings published in the journal Nature Neuroscience.They did not react the same way to other odours, and compared to the offspring of non-trained mice, their reaction to the cherry blossom whiff was about 200 percent stronger, he said.
The scientists then looked at a gene, M71, that governs the functioning of an odour receptor in the nose that responds specifically to the cherry blossom smell. The gene, inherited through the sperm of trained mice, had undergone no change to its DNA encoding, the team found. But the gene did carry epigenetic marks that could alter its behaviour and cause it to be "expressed more" in descendants, said Dias.This in turn caused a physical change in the brains of the trained mice, their sons and grandsons, who all had a larger glomerulus—a section in the olfactory (smell) unit of the brain.

In the case of humans with different environmental exposures, Fraga et al.[94] studied young monozygotic (identical) twins and older monozygotic twins. They found that although such twins were epigenetically indistinguishable during their early years, older twins had remarkable differences in the overall content and genomic distribution of 5-methylcytosine DNA and histone acetylation. The twin pairs who had spent less of their lifetime together and/or had greater differences in their medical histories were those who showed the largest differences in their levels of 5methylcytosine DNA and acetylation of histones H3 and H4.

More than 100 cases of transgenerational epigenetic inheritance phenomena have been reported in a wide range of organisms, including prokaryotes, plants, and animals.[95] For instance, Mourning Cloak butterflies will change color through hormone changes in response to experimentation of varying temperatures.[96]

Recent analyses have suggested that members of the APOBEC/AID family of cytosine deaminases are capable of simultaneously mediating genetic and epigenetic inheritance using similar molecular mechanisms.[97]

The wiki on epigenetics is interesting, shows how heritable characteristics are an extremely complex process involving many different mutation dynamics and can be preserved by sexual selection. Instinct for example is probably the result of DNA methylisation which affects how memory works, so that behviours can survive to ancestors, gradually building into something like the fight or flight response for example.

I recently saw a twin study on obesity, and it is quite remarkable that even when sharing identical DNA, some twins can have a propensity to obesity and some twins do not, and it is purely it hence seems due to environment. You would expect since obesity is partially genetic, that sharing such likelihoods of obesity would mean both twins became fat, but this is not the case. As in all things genetic there is always a spectrum of phenotype rather than a black and white you will be this.

Another interesting study suggested the reason why homosexuality survives despite it can't obviously be selectively fit and is likely to lead the person in question to have no children, is not because it is detrimental, on the contrary close female siblings of homosexual men, cousins etc tend to have more children, suggesting the genes involved promote attraction to men and greater libido rather than attraction per se.

There's also the fact that even if separated at birth the more male children you have the more likely it becomes that one of them will be gay. Which seems to be me quite a good strategy since too many cocks spoil the broth.

Lesbian women seem to find the scent of men rather disgusting, much more so than bisexual or straight women. It's a wonderfully odd world we live in.