Has behavior of a reproducing organism affected the genes it passes to its offspring? As far as I know random mutations + survival of the fittest have drawn the timeline of living things, but it almost seems too perfect if behavior affects genes that are passed, with this ability being an eventual product of static gene evolution. How do we know that this is not happening? It would explain so much rapid changes if evolution itself can evolve.
The theory is one proposed by Lysenko,
This was the idea that repeated events experienced by parents influence the characteristics of offspring; i.e. keep cutting off the tails off a group of lizards, and their offspring will eventually hatch without tails. You can see why this theory would appeal to the communist true believers, that raising a dfew generations of the ideal soviet citizen would eventually lead to all citizens being naturally (genetically) inclined to be good communist citizens.
There are some elementary issues - obviously poor nutrition during pregnancy results in problems with the fetus, as does stress or issues like lead poisoning. Some chemicals can produce genetic damage, which is then a permanent feature of future descendants.
Why do Jewish baby boys still need to be circumcised?
I believe the only behavior influencing evolution is the behavior that leads to being granted a Darwin Award.
The term you’re looking for is ‘epigenetics’.
Behaviour and environment can influence gene expression, though not the DNA sequence, and these changes can be heritable.
Gene expression refers to how often or when proteins are created from the instructions within your genes. While genetic changes can alter which protein is made, epigenetic changes affect gene expression to turn genes “on” and “off.” Since your environment and behaviors, such as diet and exercise, can result in epigenetic changes, it is easy to see the connection between your genes and your behaviors and environment.
In recent years, the belief that the genetic code is the sole basis for biological inheritance has been challenged by the discovery of trans-generational epigenetic inheritance. Environmentally induced phenotypes can in this way persist for several generations, due to the transmission of molecular factors that determine how DNA is read and expressed (Jablonka and Raz 2009; Bonduriansky and Day 2009). Epigenetic regulation of gene expression is a common process that acts during the differentiation of somatic cells, as well as in response to environmental cues and stresses, and the passing on of these modulations to the offspring constitutes epigenetic inheritance.
Yes. Look at the mating behaviours of birds such as Bower Birds (or almost any sort of birds).
Mates are selected on the basis of behaviour; genes and developmental factors drive that behaviour, but it’s the behaviour, not the genes, that are proximally subject to selection.
Edit: I mean, in a broader sense, it’s never the genes that are really selected because genes are just chemicals; it’s the expression of the genes that is subject to selection - and that expression can take different forms such as physical appearance, metabolic characteristics, behaviour, etc.
BUT, those expressions can be selected by natural and environmental factors, or by other things such as the behaviours themselves, in other members of the population.
But wouldn’t evolution eventually favor the species that had its genes changed based on the behavior on the individual’s ability to adapt? I mean, we see this in a macro way as humans, why can’t this be an explanation of the relatively rapid progress of species? Even Darwin’s birds, for some bird to be so dominate at gathering food because of a mutation, and that mutation somehow producing a mono culture of the same mutation that eventually kills off other 99.999% similar birds that were fine w/o the mutation just seems lacking. Macro evolution stems from “micro” evolution but the explanation of how that happens within just a few thousand generations is lacking.
A few thousand generations can be a long time.
Take a simple example. Suppose that in a certain species of bird, longer beaks give a slightly better chance of survival. Suppose that, as a result, the average beak length across the whole species increases by just one tenth of a millimetre each generation. In a thousand generations the average beak length will have increased by 10cm.
There are changes in human genetics that have happened over only a few thousand years in some populations, in adaptations to living at high altitude:
General purpose adaptability has evolved multiple times - humans, crows, parrots, cephalopods and probably quite a few other cases that aren’t springing to mind right now.
Ultimately, it seems like you might be asking ‘why do organisms do something that doesn’t look to me like it is a successful thing to do?’
If it were not successful, they would not be here for you to comment on.
If a method arose for genes to change based on behavior, those genes might be favored. But genes happen randomly, and not every “ability” is plausible. Sometimes there just isn’t a path from “here” to “there”.
The closest we have is epigenetics. A lot of development depends on which genes are turned off and on, and genes are, for various reasons, turned off and on due to external factors, which means they, in a way are influenced by behavior. Some of those on and offs can pass on to later generations. (For details read the links provided earlier.)
There is usually room for any organism to behave slightly sub-optimally. In times of plenty potentially quite a bit of room. The idea that every organism we observe has been perfectly honed by evolution for the conditions we find them in is a misreading of the idea. Conditions change, and organisms won’t evolve instantly, nor do they need to evolve perfectly, they only need to evolve well enough.
It would appear that epigenetics are an evolved mechanism that allows organisms wiggle room to pass behaviours to progeny, but it is more a matter of passing some existing parameter settings, which are within a limited range defined by the set of genes being controlled. There isn’t any mechanism for extending epigenetic processes to real evolution, that is producing a new species of the organism. That still requires mutation of genes. You might get an organism with parameter setting that have never been seen before, but it is still the same species, and if conditions revert, epigenetic changes will revert the species behaviour. You won’t get a new species.
Clearly early evolution has produced an underlying set of mechanisms that control the genetics of organisms that is good at sucessful evolution. Sexual reproduction was probably the really big jump in evolution that really set things up for fast and productive evolution. Rates of mutation themselves may be selected for, and times of plenty may favour higher rates of mutation. But one would expect that to be a slow change.
Individuals don’t evolve, populations do. As pointed out upthread, populations that migrate to higher latitudes or higher altitudes enter environments that may favor adaptation.
Making evolution political might not be ‘perfect’.
Partly because the rabbis insist on it. I was born without a foreskin, but they insisted on cutting enough to draw blood. One of my son’s was too and we never put him through that.
I wonder how frequently that happens.
The point here is that evolution (usually) happens in small steps. That one bird that has the mutation for a longer beak (or the animal with the longer neck, on its way to being a giraffe) has a minor advantage. They eat a bit better - can reach deeper in the cone for seeds, or higher for leaves. In difficult times, this means they eat better and produce more offspring.
But they produce them with normal members of the species. so the special gene is mixed and amtched with many others. Meanwhile, it would take several generations, including genetic drift and crossovers during meosis, so that gene is not only from one particular parent - it is mixed in with genes from dozens of others as a great-great-etc.-grandparent to a plethora of offspring. Next drought or bad weather, these survive. And of these, perhaps a few have the gene doubled up from both parents (if not on the X or Y) and have even longer beaks, or there’s a follow-up mutation that results in a longer beak/neck. If the mutation gives even a tiny advantage, it’s like compound interest. A half-percent better survival rate to live to breed means it slowly becomes the more common characteristic.
We see this opposite in the “hobbits” of Java or the miniature elephants of Malta (now both extinct). stuck on an island with limited resources, the smaller ones who needed less to survive were the genetic winners during difficult times. Each go-round, the average size winnows down and becomes smaller until the average human on the island was about 3 feet tall; or elephants only 5 feet tall.
This selection lottery requires, of course, that the characteristic have an inheritable genetic cause.
There are other ways to win the selection lottery though - humans have been passing on heritable characteristics by mechanisms other than genetics. Culture, education and technology are ways for a species to pass things to their offspring, which may confer a survival advantage and are still subject to selection, but are not carried in the genes.
I think there are observed cases of this in wild animal populations too - where an individual of a species learned to do something novel that was advantageous and others in the population learned it from that individual.
Which brings us to memes. If a gene’s prime objective is to be passed on, so is a meme’s. Evolution doesn’t care how the trait is encoded, just that it is passed on and can mutate. But we don’t count the memetic code as part of what makes a species, even if loss of some part of that behaviour information might actually lead the species to fail.
The other point to make is… evolution. Some action or behaviour may trigger something in the offspring that is advantageous. But presumably, that’s as far as it goes. It’s not like this means each succeeding generation will have more and bigger or longer of whatever than the previous generation, it’s just a one-time change.
Sexual selection and mate selection are the largest way that an organism affects what genes it passes on to its offspring. As far as I know, there aren’t any organisms that can decide which of their own genes to pass on. (I think some animals can control the sex of their offspring, so maybe that counts if it occurs in species where sex is genetically determined.)
If the choosier sex (usually the females) picks their mates based on genetic characteristics, then they are choosing what genes to pass to their offspring.
As referenced above, in something like bower birds, this can be the mate that puts on the best mating show. Genes that increase the likelihood of putting on a good mating show will be more likely to be passed on to the next generation.
It’s also important to remember that much of evolution works on existing variation in traits. All proto-giraffes don’t have one size of neck, and then there’s a mutation and one has a long neck. Proto-giraffes have a range of neck length. Perhaps in one environment the neck length isn’t important, just random variation. Then something in the environment changes, and a long neck is more adaptive. The longer necked animals will pass on their long necks to offspring, and long necks will mate with other long necks, possibly making even longer necks. Maybe throw in a few mutations for good measure, and you get a freakish tree chomper.
Congratulations! Or rather, mazel tov! Looks like Lamarckism has worked in your family!
Several people upthread have mentioned epigenetics and how it can turn genes on or off. That’s not the only thing epigenes do. They also regulate how often a gene is expressed. Consider that the human body has about 90,000 different proteins. The body will need a specific amount of each protein and that amount usually will be different for each one and also may change as the body matures. So there needs to be various mechanisms to reduce or increase the amount. They’re usually chemicals that are attached to DNA or to a histone that DNA is wrapped around. Those mechanisms are collectively called ‘epigenetics’ and while we know about a number of them, there’s probably lots we don’t know about.