That is blatantly false. Sex speeds up evolution exponentially with population size. With sex, each beneficial mutation can spread across the species even after arising only once. With asexual reproduction, beneficial mutations are confined to that particular strain. Sex is enormously beneficial for the ability to evolve and adapt quickly. This has been confirmed by mathematical models.
Two of the models that Pepe alluded to are Mueller's Ratchet and Kondrashov's Hatchet. We know that sex is powerful because it persists despite the high cost.
Mueller's model assumes that fitness decreases as a linear function of deleterious mutations. In simplified terms: Got n bad mutations? You're more likely to reproduce than someone with (n+1) bad mutations.
In an asexual population, individuals will have the set of mutations plus those acquired by mutation from their time of divergence. When you add sex to the mix (ha!), your population stops looking so flat. It introduces variance and selection culls the maladapted individuals. What's really cool about this, is you can model the deleterious mutations being driven out of the population.
Kondrashov's model is even more powerful. Basically, it says that there's some capacity for deleterious mutations. A couple of things wrong? Yeah, you'll reproduce. Too many? Well, you stepped off an mutational cliff and you aren't long for the world. This step function actually removes deleterious mutations from the population faster than Mueller.
The advantage of sex is obvious even on an individual basis. We all should have a chromosome that's "worse than average". When you mix and match them among your gametes, you'll end up with some non-viable gametes and some superstars. By failing fast, any parental investment can go toward offspring who are more likely themselves to be viable.
[For more information, check out Gillespie's Population Genetics]
1. Mueller's ratchet is still a hypothesis. A well supported hypothesis, but there are cases that it doesn't yet explain (Bdelloid rotifers, for example).
2. Even accepting the premise, it doesn't explain why sexual reproduction should be favored over asexual reproduction with occasional conjugation.
3. Even assuming that this mechanism is sufficient to explain the advantages of sexual reproduction, it still operates over a long time scale (i.e. long enough for enough deleterious mutations to accumulate in the asexual reproducing population).
What this comment and the parent (and many of the others in this thread) fail to understand is that no one is debating that sexual reproduction is advantageous over long enough time scales. The question that the authors of the original paper are addressing is how sexual reproduction could be advantageous enough on a short enough time scale sufficient for those organisms to avoid being outcompeted by asexual organisms.
What this comment fails to understand is that I was explaining mathematical models for sexual reproduction to an audience who might otherwise be unfamiliar with it. Any inference that I was making claims about the relative efficacy of sex is sorely mistaken.
Finally, this house would like to remind the honorable gentleman that he is invited to comport himself in a civil manner.
Apologies and much appreciation for the introduction of some interesting, and very much important, models from evolutionary biology. I fear my tone was somewhat poisoned by that of the grandparent comment. Wanting to learn about evolution is fine. Doing so by asserting that certain accepted "truths" might not hold is also perfectly valid (assuming you're willing to accept when you are wrong).
Claiming that the entire premise of a course of research, on which numerous scientists with extensive training have worked, is "false" is just filled with the worst sort of hubris.
Leaving claims of hubris aside, I think some of the sibling threads are a tad mistaken. For example, population size is a determiner of the rate of neutral drift. I'm trying to work through what are the implications to having more genealogical ancestors than genetic ancestors, but it isn't immediately clear.
If you really want your mind blown, check out Art Poon's paper "The Rate of Compensatory Mutation in the DNA Bacteriophage φX174" and Daniel Weinreich's "Darwinian evolution can follow only very few mutational paths to fitter proteins". Both have some amazing evolutionary implications.
This was my immediate reaction as well, although I'm not sure I would dismiss the article as "false". Since there seems to be a significant amount of misunderstanding of what PepeGomez is saying in the rest of this subthread, I'll take a crack at an explanation.
One way to understand is to look backwards at a single individual's ancestors. In an asexually reproducing species, the number of ancestors is O(n) in the number of generations you look back – and in any prior generation the individual has exactly one ancestor. In a sexually reproducing species, the number of ancestors is O(2^n) until you reach the point (surprisingly rapidly) where the whole species either is an ancestor or doesn't have any surviving descendants.
Why does this matter? Because multiple beneficial mutations are far more likely to have arisen in the O(2^n) ancestors in the sexual scenario than in the O(n) ancestors in the asexual scenario. In other words, sexual reproduction allows beneficial mutations to occur independently in any pair of unrelated individuals in a population and eventually both mutations will spread to the whole population – the whole species ends up with all the "winning" mutations. With asexual reproduction, unless two mutations just happen to fall on the same lineage – which is very unlikely – they will compete instead of merging, because there is no mechanism for merging lineages.
Bottom line: in asexual reproduction, independent mutations compete; in sexual reproduction, they can cooperate. Sexual species literally evolve exponentially faster than asexual ones.
Except that's not how evolution works. You can't just randomly decide to "count backward" and you definitely can't ignore the fact that ancestors overlap. You might look up "The 7 Daughters of Eve". In short: all humans alive today descended from just 7 women, but those 7 women were not the only women alive at the time. All the other women living at the same time as the 7 had their genetic information lost to the sands of time.
The Seven Daughters of Eve is about mitochondrial genetics. Mitochondrial DNA is inherited only from mothers, so the inheritance pattern of mtDNA is exactly like that of an asexually reproducing species. So yes, you can trace the mitochondrial ancestry of each person alive today back to exactly one of the "seven daughters of eve" and the mtDNA of all the other women alive at that time died out. But that doesn't mean that the rest of their genetic material didn't survive. Any woman who had only sons – no matter how many sons she had, or how reproductively successful they were – appears to have died out from the mitochondrial perspective. For that matter, from the mitochondrial view, every man who has ever lived failed to reproduce. Obviously that's not the case when we look at the full picture of all of our genetic material. There's a lot of focus on the mtDNA and Y chromosome lineages because they're linear and therefore relatively static (i.e. evolve at a slow, predictable rate), but it's important to keep in mind that this isn't how most of our genetic material behaves. In particular, you cannot understand sexual genetics by studying mtDNA and Y chromosome inheritance because those lineages are asexual, which is precisely why they are easier to study.
I downvoted you because although individual points of the article can argued, the text is certainly not "blatantly false" and the overall dismissive attitude is harmful to potential discussion about nuances of the issue.
It's premise, that the costs of sex obviously outweigh the benefits, is false. Sex is an extremely advantageous ability. There is no discussion to be had, because the assumed problem doesn't in fact exist.
What does punctuated equilibrum have to do with it?
The costs aren't heavy, the math in the article is wrong. Yes, each of your offspring will have half of your genes, but twice as many offspring counts as yours.
Punctuated equilibrium is a reaction to your claim that evolution speeds up exponentialy with the size of the population. In practice, it's more like you need very small, separated group to move things forward. It's explained by the fact that one gene contribution to fitness is heavily dependent on other genes, so an in-one-context-advantageous mutation has problems with crossing-over destroying some conditions of its success.
Oh that, yes, but that's exactly what sex allows to happen. Imagine there are three populations of desert flowers, each with its own adaptations to drought. One population has mutations a and b, other has c and the last one has d and e. When these populations meet, their genes recombine and in a few generations there will be individuals with all five, much more resistant than any of the parent groups.
This is entirely impossible with asexual species - the strains would merely compete with each other and nothing interesting would happen.
Consider a startup. In the long run, it may have a large advantage over its incumbent competitors. But at inception, it often needs a capital investment to overcome a barrier of entry. Without the initial investment, the startup may never see the light of day. The article's thesis is analogous: though sexual selection may be a global maximum, evolution might have gotten stuck in a local maximum (asexual selection) if not for a little boost.
Off the top of my head, I can imagine possible adaptations which humans would find strictly beneficial, but we won't likely evolve (without genetic engineering). E.g. there's no good reason why humans have a blind spot. We wouldn't have it if our optic nerves were attached behind our retina instead of in front. But we're stuck with it because evolution can't conjure a discontinuous jump in our anatomy.
I wish it was that clear cut. This is a tricky business in the sciences. Often, the quantity you are trying to validate is unobservable. In this case, I suspect (I'm not a squishy scientist) it is because evolution has such long time scales.
In other fields, it can be simply because it is prohibitively difficult or expensive to instrument the quantity of interest. This is extremely common, even in the 'hard' scientific fields and engineering. You very, very seldom have all the data you want.
This is all a long winded way of saying that confirmation of a hypothesis by mathematical models certainly is a mechanism by which science creates a stronger degree of belief in said hypothesis. Would it be a full fledged validation of the model? Probably not. But it is absolutely useful evidence.
I'm a computational scientist too, but those mathematical models don't provide confirmation. It certainly can help build evidence, and when a model starts to make predictions outside of the model, then we really can a lot of confidence in it. But a model is just a model, and unless the universe is truly mathematical in structure (not a completely crazy idea), and our models match that structure, then they can't really confirm anything.
I think Popper's concept of Falsificationism is best put by Asimov in his essay The Relativity of Wrong [0]. The thesis is that Science never has the perfect model. Instead of directly arriving at The Truth, it continuously refines imperfect models by reducing error. In this view, the difference between "confirm" and "provide evidence for" is simply a matter of degree.
All good points, and I think we are entering into philosophy around what we mean by 'confirmation'.
I believe that models are certainly wrong. I personally doubt we have any models that actually reproduce the underlying mathematical structure of the universe (if it even exists, as you noted).
...But some models are useful. And when viewed from that perspective, a mathematical model can provide evidence that a hypothesis accurately explains an observed phenomenon, given a certain set of assumptions.
I view validation of a model hierarchically, where a untested hypothesis gains credibility by increasing tests of the validity of its predictions. Direct experimental confirmation is the strongest, but this is almost always impossible, and so weaker forms of testing are necessary. Computational modeling certainly provides a weaker form of confirmation, from this perspective.
You're misunderstanding how gene flow works. Consider one individual with one advantageous mutation that has 1000 offspring. In an asexual organism all 1000 will contain the mutation (minus any small frequency of the mutation spontaneously reverting). In a sexual organism only 500 will carry the advantage.
No, that is not correct. A hermaphrodite species will all things being the same have twice as many offspring as an asexual species, in your example 1000 from its eggs, 1000 from its sperm. In a strictly male/female species, a successful female will indeed likely spread the genes half as fast, but a succesful male can spread them much faster.
But this is with only one gene. Imagine there are five a, b, c, d and e. An individual with all five will arise much sooner in a sexual species.
The evolution of sex isn't a mystery any more than an eye is a mystery. It's not all or nothing. Life didn't go from bacteria to peacocks in one step. You can have something like optional hermaphrodite sex (in mollusks, I think) where you can exchange genes when the conditions arise, but it's not mandatory. The costs are virtually zero, but the benefits are still there. But then it becomes advantageous for idividuals to cheat and impregnate others, without producing eggs themselves and you get separate sexes.
Absolute numbers don't matter, only frequency, as in evolution you have to assume that individuals are reproducing fast enough to exceed the carrying capacity of the environment.
And yes, once you get to more mutations then sex is more advantageous for a number of reasons. No one is claiming that sex is not better over long enough time scales. The question is how can it be advantageous enough to become fixed in a population over the span of a couple generations.
And yes, sex did evolve gradually. Slime molds have optional sex (and more than 2 sexes!). But still keeping the machinery around is expensive. One would expect that individuals that ditched it would outcompete those that kept lugging it around unless there was a relatively short-term benefit to sex.
Exactly, in a stable population, one offspring of each individual survives on average in an asexual species. Two with half of your genes each survive in a sexual species.
It doesn't need a long timescale, asexual species get out-evolved by sexual species and go extinct eventually. Sexual species have a much higher probability of entering new niches or surviving when the conditions change. This can be seen in many species that reproduce asexually when the conditions are good, but reproduce sexually when stressed.
A species that loses the ability to reproduce sexually is doomed to extinction. Asexual reproduction is essentially putting all your eggs into one basket. When you die of a disease for example, chances are that most of your offspring dies as well AND there is a much higher chance that the disease adapts to your genome in the first place. This can be seen in agriculture, where plants are reproduced asexually to a much bigger extent than what would happen naturally. Many are impossible to grow without heavy doses of pesticides, as the diseases quickly adapted to the commonly planted strains. The strains need to be replaced every few decades, before growing them becomes essentially impossible, even with pesticides. Evolution is much faster than you assume.
You can't look at a single individual. Even as soon as you include two individuals with advantageous mutations, the chance of them having an off spring with both is extremely higher than for an asexual organism.
Scale this up to 1000 individuals, each with mutations that are advantageous or disadvantageous, which impacts their chance to have children, and run it across a few generations (with a small chance of children getting new mutations not in their parents), and the chance of a subset of the population getting many of the positive mutations is much much higher than if they were an asexual species.
The asexual species will end up with more member of the final population having the single most advantageous mutation, but with none having more than that.
This individual invariably carries ten of disadvantageous mutations too. It will pass all ten to offspring when reproducing asexually, but only five of them on average to every sexually-produced offspring, and a dozen will only get 2 or 3 such bad mutations.
This arithmetic becomes ugly fast for asexual reproduction.
Again, it's the exact opposite. In an asexual species, a disadvantageous mutation will be flushed from the population very quickly, as those without the mutation will outcompete those with. You'll never get an individual with ten disadvantages.
On the other hand, in a sexually reproducing organism, a disadvantageous mutation can be masked if recessive, and selective pressure will only remove homozygotes from the population. The end result is that harmful mutations can stick around for a long time, and even accumulate in individuals.
Correct. Sex is advantageous over the long term. This is not up for debate. The question is how to compensate for the considerable costs in the short term so that sexual organisms are not immediately outcompeted by asexual organisms.
Asexual organisms can outcompete some part of population, but doubtfully all of it. And their competitive advantage shrinks as their numbers grow, due to clone interference.
A lot of insects can reproduce asexually but they are also capable of sexual reproduction. Ones who are not eventually die off.
You're assuming that a population of asexual organisms was mixed with a population of sexual organisms. In reality, asexual reproduction came first, so the inability of asexual reproduction to overcome a large contingent of sexual organisms is irrelevant.
And yes, optional sex is almost certainly how sexual reproduction arose. Even today I'd wager there are more facultatively sexual organisms than obligate sexual. That's a non-sequiter, though, as even optional sex would be bred out of a population if it could not show a benefit in a small number of generations.
Imagine three populations of desert plants. One survives by growing longer roots and storing more water. Another has roots that can extract water from dryer soil. The third is adapted by breathing during the night and losing less water.
It's obvious how a sexual plant that is able to obtain the beneficial mutations from the other two populations would gain a major and immediate advanage.
We all agree that sexual reproduction is advantageous over a long time scale. The question is what about a short time scale. Even with selective breeding, it'll be at least two (and more likely 3-5) generations before you could get all three advantageous traits in the same plant. With random partnering as would happen in the wild it could easily take an order of magnitude longer.
This paper presents a hypothesis that explains how sexual reproduction could be more advantageous than asexual reproduction after one generation. This is what makes it novel and new.
How more short term would you want it to be? The trait doesn't have to be advantageous every single generation in order to spread.
It's two generation with or without selective breeding. The first generation will have individuals with three or four beneficial mutations, the second will have some with five. (assuming the traits are dominant)
A lot of experts disagree with you that this is an open-and shut-question, including leaders in the field of population genetics. It is by no means so clear cut.
Below I've linked a nice blog post on the question, as well as a Nature review from 2002 and even a Nature article from two weeks ago (Mar 2016).
"The vast majority of species engage in some form of sex or genetic exchange. Yet the evolutionary forces that make sex widespread in nature remain incompletely understood. In principle, asexual reproduction should be more efficient: it avoids the costs of mating and allows individuals to pass all (rather than half) of their genetic material to their offspring. Extensive theoretical work has sought to understand why sex is pervasive despite these substantial costs."
No matter how big experts they are, they can't disagree with math. Asexual species pass on all their genetic material to half the number of offspring. In a stable population, one offspring on average survives in asexual reproduction, two in sexual reproduction. In other words, while you pass half of the genes per offspring, twice as many offspring is technically yours. The amount of genetic material passed on average remains the same.
The amount of genetic material passed on does not remain the same. Each offspring is an independent event, and which half of the genes gets passed along is selected randomly. So if an asexual organism has genes "A B C", then both it's two offspring will get "A B C". If a sexual organism has genes "Aa Bb Cc", and its first offspring inherits "A b C" from that parent, the second offspring could inherit "a b c" in which case the "B" allele is lost.
But that's not the argument they're making, the argument they're making is that the amount of passed genetic information is halved, because they fail to take into account that every offspring has two parents in sexual reproduction.
I've avoided doing so until now, but at this point I have to assume that you've only read the introductory paragraph of TFA and no further. The comment about only passing on half of an individual's genes is the author attempting (and not completely succeeding) to relate the well known, well studied costs of sexual reproduction to a lay audience.
This is not, however, what TFA is about. It is covering a course of research that is investigating whether or not sexual reproduction compensates for the difference in mutation rates between mitochondrial and nuclear DNA. You've managed to fill an entire thread with attacks on the introductory paragraph from a science journalist without once addressing the research being reported upon.
I did. If the premise of the research is invalid, the research itself must be invalid.
There is no such a cost of sexual reproduction. We need to separate sexual reproduction from having separate sexes. Hermaphrodite reproduction isn't very costly, the only cost is the cost of the sexual act itself.
Then, however, hermaphrodite reproduction is unstable, since it's obviously beneficial for the individual to only impregnate others, without prodicing eggs itself, and so passing the most expensive part of reproduction to others.
Then, the next question is why the females don't revert back to asexual reprodction, but 1. that has been observed in many species. 2. Purely asexual lineages tend to die out soon and 3. it's partially counterbalanced in many animals by the male providing some other benefit, like giving food to the female or taking care for the offspring.
While this is indeed somewhat paradoxical, it's in no way a mystery.
Another problem with this theory is that symbiosis and mutualism are not uncommon in nature. The way this problem is typically prevented (and it seems to be even a necessary condition for mutualism to remain stable, or even arise in the first place) is that there is some mechanism for culling or cutting off the symbionts that fail to provide the expected benefits. There is no reason to believe that the same isn't the case with mitochondria. Sex seems to be a very heavy handed way of doing so, and if it was so, you would expect people to die randomly without a clear reason when their mitochondria happen to mutate the wrong way.
And that recombiantion thing, that actually does happen, it's known as "outbreeding depression" and probably one of the reasons why species arise.
“Until recently, science has basically ignored the fact that we are all walking around with two genomes in every cell,” Dowling says, “that of our own nuclear genome, and that of the mitochondria.”
Really? I was taught about mitochondria in considerable detail as part of the biology part of my undergrad science degree & mitochondria have clearly been studied pretty intensively. That’s not to say that there aren’t gaps in our knowledge or new things to learn, but the idea that the mitochondria have just been ignored is clearly untrue.
I guess some researchers feel it necessary to talk up their own research though - it’s a labrat eat labrat world out there.
In my high school biology class, which I would assume is still the highest level of biology most people complete, mitochondrial DNA wasn't even mentioned. Many high school level science courses are rife with disinformation.
I definitely was taught quite a bit about mitochondria in grade 10 (Canadian) high school biology, in the early 90s. We were even told about at-the-time-speculative-now-accepted theories that mitochondria were the result of a primitive "capture" of a prokaryotic cell by the first early proto-eukaryotes.
Shortly after Dolly the Sheep became famous, Ian Wilmut (one of the main people of that project) visited my university for a talk, and I asked him if he was concerned about the impact of mitochondrial differences between the genetic donor and the host egg. He was quite dismissive, saying (IIRC) "mitochondria are responsible for at most 5% phenotypical expression".
To me that sounded like a lot (and I had asked the question because I expected mitochondrial differences to really matter) but he did not share my view.
So, yes, if Dr. Wilmut's reaction was typical, I think it's fair to call that "ignored". Not "unknown", but ignored.
This is part of a greater dehumanization[1] agenda by the parts of the US media industry. I don't have a conspiracy theory about why this is or who is behind it, but it's been going on for a few years now. Once your reticular activating system's habituation filter has opened up on something like this, you cannot not notice such articles when they pop up.
I mean, click-bait or not, the idea of referring to an innate part of the biology of animal life as a "coping mechanism" automatically leads to a form of nihilism.
did you read the article? using 'coping mechanism' in the headline reads like an intentional joke, subverting its audience's expectations
replace coping with regenerative or restructural or restorative and you have a clearer take on the article
the authors argument is a biological one
about the benefits of sex, versus asexual reproduction, encouraging and repairing mutations on a cellular level
the idea of it applying to the entire organism is only slightly touched on in the last few sentences, again, as a seemingly mocking jab at the notion of sex being a psychological 'coping mechanism'
to the effect, 'you're right it is a coping mechanism, sex copes well with evolution's affinity for variety quite well'
that said, to directly address your dehumanisation:
sex is a coping mechanism
and it is expression of self, and it is physical form of progeny creation, and it is a social construct, and a whole lot more to a whole lot of different people for different reasons
denying that sex helps some humans cope with other issues seems rather dehumanising to those people
but again, this is just addressing your comment, the article is about something completely different
I'm not so sure it's an explicit conspiracy. I think it's just an outgrowth of Nihilism -- just what naturally occurs when you're jaded towards all the traditional narratives that give meaning to life.
That's an interesting take on it. Also, thinking about how we've come to a scientific understanding of most of the things that were previously sacred magic of sorts perhaps gives us a sense of being above all of it.
I'm not religious and I'm certainly not a proponent of orthodoxy in nearly any aspect of life, but I always feel that trying to transcend naturally existing things is a fool's errand. One example is illustrated by our recent understanding of antibiotics and how they destroy our gut biome, and how that might be a really big problem.
It's been the almost universally accepted opinion in philosophy for the last 100 years or more that post-Enlightenment man is Nihilist because he denies his traditional narratives. It's the big story of the 20th century. Everything from Nazism and WW2, to the divorce rate has been blamed on it... Where have you been?
Oh no, someone doesn't know every little detail of a "universally accepted opinion" in philosophy for the past 100 years... on a technology news website. Shocking. It's almost like not everyone knows everything all the time? Interesting take on it.
Look, I overreacted. In this case, evidently, mangeletti merely misspoke. However, it's common I hear this same complete lack of humanities education in all areas of technology. It is a growing concern of mine.
I'm not worried about "every little detail". I'm concerned with basic areas of human knowledge, foundational elements of a classical education.
I'm concerned that we're creating engineering-educated drones capable of industriously automating away our traditional roles, yet who haven't even had the proper post-Enlightenment education to understand the civilization in front of their eyes.
My "interesting take on it" comment was referring to @spacehome's suggestion that the outgrowth of nihilism is the cause of the supposed emergence of these sorts of dehumanizing articles.
I get the same general feeling, and I try not to be too paranoid about it.
I think it has a lot to do with the instrumentality capitalism wants from its participants -- and we seem to want to use science to make us better cogs rather than better humans. Its a pretty old idea stemming from the industrial revolution -- it just seems that today we're more 'loosely coupled' into the system which gives us just enough of an illusion of freedom. e.g. you can choose a job, but you can't choose not to have a job, you can speak freely, but you'll be monitored etc.
Because of this I have recently had a resurgence of volunteerism and religious soul seeking. I've found it refreshing that these two arenas seek earnestly to humanize through giving.
Volunteerism and giving is great, but religion's purpose is to co-opt and channel these altruistic impulses to make people believe that good things can only come from religion (historically linked to the state). You still see this brainwashing today, with people believing that atheists cannot be moral, or that religion makes them a better person. In fact, the most religious are frequently the most immoral. Look at the widespread sexual abuse sanctioned by the Catholic Church, today and throughout history.
As an aside, OPs conspiracy theory about the article titles sounds really silly.
Your comment interests me and I'd like to learn more. What is a "reticular activating system's habituation filter"? I tried googling but all I get is a Wikipedia article about the brain stem and some new-age woo.
IANA Neuroscientist. But I believe the reticular activating system governs wakefulness and attention. It's just a fancy way of saying "once you see it, you see it everywhere".
You're operating under a false dichotomy, and frankly, it's the type of misguided reasoning in the face of new evidence that leads to farces like the Scopes trial and decades of perceived conflict between science and humanity.
Of course it can be both. That's why it's disturbing that the article completely discards the majority of human experience of sexuality, while literally saying "To understand sex completely, we need an explanation that goes back to the primordial soup of very early complex organisms and the immediate survival pressures they were under."
If by that you mean centuries, I'd agree. Dehumanization of classes of people is a feature of human civilization going back to the beginning of human civilizations. Look at the link you posted. Right at the top is a picture that proves the point.
There's no conspiracy. It's what we do, it seems, for better or worse.
This article in particular though, I don't really see it? It's biologists suggesting a model for understanding features of human evolution. It doesn't at all suggest we treat people with disrespect en masse. It doesn't at all suggest we censor a class of humans for political/economic gains.
You want to shine light on a conspiracy to dehumanize? Try going after something that matters. Like wage labor, student debt, consolidation of wealth... All which are truly dehumanizing facets of our society that impact people on a wide scale. This article is biologists comparing notes in a very limited context, with very limited power/authority to subjugate people.
This post reads like paranoid ramblings of someone unable to compartmentalize things into appropriate context.
While it is definitely too soon to consider this hypothesis even close to settled, it's not as far out as it might seem at first glance. Indeed, what we evolutionary biologists have always said is that the cost of sex is compensated for by robustness in the face of evolutionary pressure.
All this group is saying, in essence, is that instead of that pressure coming in the form of infrequent external events (plagues, floods, asteroids, etc.), it is present for every generation in the form of dealing with mitochondria that don't quite fit any longer. An interesting idea, to be sure.
I'm interested in this though: do you know any examples off the top of your head where the male passes on mitochondria? I thought the primary reasoning is that sperm is little more than DNA with a tail and engine attached. (poetically speaking)
Ah...I misunderstood your comment and I misunderstood how it works. I thought human sperm had no mitochondria. Turns out that is dramatically not the case, but the sperm's mitochondria is killed off by the egg, and that's exactly what you said.
I had thought you were saying the sperm had mitochondria and the egg killed THE EGGs mitochondria off.
Another reason why sexual reproduction is efficient is that it enables division of labour.
A mother needs to provide a complete eco-system (uterus) for the baby to live and grow which affects even the hormonal system.
A man doesn't need this, so he can use this energy or "program space" in his genome for other things.
It's one of Dawkins theses in his superb book "The selfish gene" [1] where he basically reduces evolution to game theory (without explicity saying so).
That extends to the genders' respective role in society as well, at least in humans - men being the hunters or soldiers and dying a lot, that is.
On the other hand though, in e.g. lions, it's the females that go out hunting the most. I'm not sure what the logic is there. Maybe the males die a lot in fights for dominance and territory so they get to be lazy?
Up until recently, women died a lot… giving birth.
(It really comes to life when you read about history and queens or the classic plays and fairytales where there's so many remarried older men)
Maybe the lion case is also a "social effect" since a male lion is either completely alone or he is the leader of a pack of not so few females + cubs.
I suppose the lone lions hunt for themselves (and you probably didn't count those) while the leader of a pack doesn't need to because he is the respected, well, leader.
All that is probably true, but the thesis has one flaw. While the benefits of sexual reproduction tend to be subtle and become evident only over many generations, its costs are heavy and immediate.
But isn't the "flaw" already taken care of: the heavy and immediate costs are very much compensated by the pleasure and high stimulus which are as immediate as anyone who has gone through puberty knows. (And which are not unknown in the non-human part of the animal world either.)
You should continue. The article discuss the relation between the nucleus ADN, the mitochondrial ADN and sex. I'm still not convinced about the conclusions, but it's an interesting theory.
I really don't like the title, it looks like a confusing linkbait. Following the unofficial extended guidelines, I suggest the subtitle that is much better: "Did sexual reproduction evolve to keep up with mitochondrial mutation? "
Off topic.I am student and in last year I felt this drawback.I spent almost all of my day reading internet (scientific material, watching courses).But recently I can feel internet makes person a shallow, without deep understanding about topics.(I don't know how to express clearly). I recently completely switched from internet to reading exclusively book/papers.
Exactly, because there are huge differences between people in HN and other people on the internet. most (not all) stuff in HN is quite good and the links to books/papers are my favorite ones.
The article is full of gross approximations and falsehoods. The author later states things like
That link lies in the fact that mitochondria are not just cellular batteries. Billions of years ago they were actually independent organisms. They are an example of how the human body is not entirely “human.”
and (quoting someone else):
“Until recently, science has basically ignored the fact that we are all walking around with two genomes in every cell,” Dowling says, “that of our own nuclear genome, and that of the mitochondria.”
