Human sperm cooperate on the competitive pathway to fertilization: study | Hacker News Reader

Human sperm cooperate on the competitive pathway to fertilization: study

nautil.us

168 pointsdnetesn102 comments

Animals' shared ancestor with fungus is thought to be among https://en.m.wikipedia.org/wiki/Choanoflagellate, which kinda look like sperm.

My guess is that they were predominantly haploid (like sperm/eggs), and just had a diploid (like most other human cells) phase for reproduction. Somewhere along the way this switched (which is thought to have happened in plants also, mosses are primarily haploid while flowering plants are primarily diploid).

...which is totally bonkers. It's like if sperm/eggs went around making all of the important decisions and only bothered to spin up a human briefly for reproductive purposes. But then the sex got a bit out of control and got a job and an apartment and now it's the sperm who look like they're just for reproduction.

Disclaimer: I took Bio 101 two semesters back, so I'm pretty much an expert.

Your comment reminds me of another biology tale:

The natural, most efficient, and optimal state of an animal is napping.

Wakefulness, and everything that happens during that time, is just an annoying distraction to maintain homeostasis.

That is the natural state of the domesticated cat because we have artificially selected them to match our aspirations. The optimal nappers. They’re awake just long enough to remind us that they’re the boss and our sole function is to feed them.

Are you sure thats not just the toxoplasmosis gondii talking?

[0]:https://en.wikipedia.org/wiki/Toxoplasma_gondii#Behavioral_d...

No, but it would explain the irresistible urge to poop in a sandbox.

> It's like if *humans* went around making all of the important decisions and only bothered to spin up a *machine* briefly for reproductive purposes. But then the sex *bot* got a bit out of control and got a job and an apartment and now it's the humans who look like they're just for reproduction.

This perspective could kind of also apply to plants, a la The Botany of Desire (good book). From a certain plant's perspective, humans exist to help them reproduce.

You can go even further: https://en.wikipedia.org/wiki/Gene-centered_view_of_evolutio...

I subscribe to that view, but I don't think it's any more wild than https://en.wikipedia.org/wiki/Alternation_of_generations

Sure, it's the genes that are doing all of this, but the fact that they would chose two totally separate body plans, each which is a reproductive system for the other... It just seems a bit too scifi to be real.

> It's like if sperm/eggs went around making all of the important decisions and only bothered to spin up a human briefly for reproductive purposes.

That's very close to the thesis of Richard Dawkins' seminal book, the Selfish Gene--we're just machines constructed by genes to replicate them. It's literally true, of course, but we don't often take that perspective; yet many things in biology aren't intuitive unless and until we do.[1]

[1] OTOH, some things in biology become inexplicable when we do take that perspective, such as non-kin altruism. IIRC, Dawkins admits as much in the book. (Contra some subsequent sociopolitical interpretations, Dawkins never used his "selfish gene" model to refute the possibility of non-kin altruism, just that the model in isolation was insufficient to explain non-kin altruism, the existence of which he seemed to take for granted, at least in humans.)

>seminal book

Don't think that we don't see this.

Reminds me of a Tweet circa 2021 where someone asked if they should stop using the word seminal because it might micro-harm people.

Pie’s Law still holds strong

I've seen people sensor themself on the word "retarded" in a physics context. Which.... Is absurd.

Yea there was a lot of that going around

Sensor themeselves? I’m incensed. :P

A company I was at renamed master to main to avoid implications of human slavery when committing to source control.

I've experienced similar. Sure, words matter. But so does context, at least it should.

And yet I bet those you make the suggestion still say "master bedroom" (which actual is a direct reference to slavery).

American home ownership is so loaded with plantation era subtle subjugation in the form of linguistic convention. If master bedroom were the worst it would get attention.

I switched to originating new repos as main instead of master personally, reinforcing the concept of “commuting to” or code “being committed” to “master”, seems diametrically opposed to progress.

In San Francisco, when I was looking for a new place to rent in 2022, the realtor would use the phrase "primary bedroom" instead, remarking that apparently people in the field are moving away here from "master" because of the connotation.

Personally, my favourite is this Github repo https://github.com/queer/boxxy

The primary branch is called "mistress". haha, that's good

On the flip side, there are also cases where some changes to the language make things more obvious and simple. As a non-native English speaker, allowlist/denylist make more sense to me than whitelist/blacklist, since allow/deny describe the purpose well, as opposed to white/black.

As for having a "main" branch or other things like that, I don't really mind the change much. Admittedly, both the claims about implications surrounding slavery and counter-arguments regarding names like having a "master record" seem overblown to me (on one side, why care about some obscure software term instead of trying to effect actual change? on the other, why push back against a trivial change so much, it's not like using a different term is so hard if it pleases a lot of people?), although perhaps due to me not having the heritage of the people in the US, so I just quiet down and do the sensible thing.

It’s divisive. Almost nobody involved in this kinda stuff is at all curious how actual slaves thought about language.

People just want an in group and an out group. And there’s an endless parade of grifters willing to provide that.

I didn’t push back or complain, but I don’t really get the victory they think they achieved there. Definitely nothing that helped an actual living person improve their life - donating the equivalent in salary spent working on the change to local families would have been more effective at making the world a better place imho. There were no theoretically impacted people championing or asking for the change. It was just some people looking for something to do, and they even had a celebration at the end like they really achieved something.

Because it’s the same group of people who want to, on a whim, decide that “homeless” is now “houseless” and that it’s offensive to homeless people to call them anything else. It’s language authoritarianism used to arbitrarily paint people as bad for utilizing common verbiage and for the dictators to feel they’re some revolutionaries all while never doing anything to actually help the people they claim to be fighting for.

The changing of the word "homeless" isn't to prevent offence, but to make people view them differently, for a time.

Isn't non kin altruism just prisoners dilemma part of the evolution? E.g. groups that work together will survive and genes of these groups will get passed on. So the desire is to help any friendly individuals, but it also works globally because this hasn't really even been part of evolution to be so globalized.

Not exactly, but also yes. There is a game being played where there are local optimums of a ratio of cooperating/betraying and evolutionary pressure against the “wrong” ratios. There is also the problem of it being difficult or too resource intensive to have perfect knowledge of what other individuals actually share your genes and by how much and some group altruism is explained by evolution taking shortcuts that work well enough.

The point of the book is that the mechanism explaining such things shouldn’t stop at “because it’s good for the group” instead digging down into why what’s good for the genes must explain the higher order behavior.

non-kin altruism could just be a mistake. A behaviour intended to be applied to ones own species, but ends up applied to others because of the detectors used to identify another agent not being scrutinous enough.

Just because you get diabetes doesnt mean its the intended behaviour of evolution. Could be a spandrel, or an artifact, or aliasing, or a plain mistake.

I'm something of a scientist myself*, and every time I delve into cellular biology I find myself wondering if there is a primitive consciousness on the cellular level, because lives of many cells are complicated.

Consider Memory B cells, which are formed early during foetal development. They hang around in the body for years - sometimes decades - looking out for new and unusual pathogens. When they encounter one, they internalize the peptides and then (typically, but not always) rush off to a germinal center to help manufacture new T cells that can recognize and defeat the unwanted interloper. then the B cells leave again and go back to their vigil.

https://en.wikipedia.org/wiki/Memory_B_cell

Conversely, when you look at the dynamics of large groups, organizations, and corporate entities (institutions as well as business, up to whole nations), it's hard not to see them as organisms in their own right that have a sort of meta-consciousness independent of their component humans.

* This is a joke

I have that thought quite often, both for cells and for aggregate things like countries or religions.

Most recently I found myself framing zoonotic diseases (e.g. Lyme, Covid, Malaria) as ecosystem-level weapons against habitat loss i.e. as a manufactured reason to keep humans away.

As an expert myself, I say both of you deserve the Ig Nobel.

> I have that thought quite often, both for cells and for aggregate things like countries or religions.

You both might find this interesting :)

Information Closure Theory of Consciousness (2020) https://www.researchgate.net/publication/342956066_Informati...

> However, only information processed at specific scales of coarse-graining appears to be available for conscious awareness. We do not have direct experience of information available at the scale of individual neurons, which is noisy and highly stochastic. Neither do we have experience of more macro-scale interactions, such as interpersonal communications. Neurophysiological evidence suggests that conscious experiences co-vary with information encoded in coarse-grained neural states such as the firing pattern of a population of neurons. In this article, we introduce a new informational theory of consciousness: Information Closure Theory of Consciousness (ICT)

Still watching the seminars, but this is the clearest text summary I've found online so far: https://www.reddit.com/r/MachineLearning/comments/dco3t1/com...

Isn’t another explanation that they travel in such large amounts they will eventually interact with the right system due to chemical interactions? That is the right proteins will activate the right channels eventually when you have hundreds of thousands of attempts? I don’t think they are conscious in the sense they are driving along a road and know where to turn. It’s all chemical signaling and statistics.

I travel in such large amounts that I eventually interact with the right systems. I have some neat meta processes for changing direction and re-orienting myself on a couple of important goals for my existence. It’s not really conscious when I change direction, it’s just kinda natural. I end up being like “whoa that was a big change.”

You might like the book Transformer: The Deep Chemistry of Life and Death by Nick Lane. (anyone enjoying this comment section would) but specifically he presents some really cool interesting ideas related to this and metabolism

A joke from one of the greatest Spider-Man movies of all time, so you get a pass

I can’t remember where I’ve seen it but there’s some interesting work done Michael Levin in this space. Something along the lines of how cells alone can have a goal but within a group exhibit different goals. This can go from cell to tissue to organ, all the way up to society. I’m not a biologist so I’m butchering his ideas, just writing this if anyone finds it interesting to look him up.

> I find myself wondering if there is a primitive consciousness on the cellular level

Has anyone seriously tried tackling this with fiction?

Possibly, although I always thought Osmosis Jones was a documentary.

Right cells of a single individual co-operate, why should sperm-cells be any different.

Yes and no. What's different about sperm-cells is you would expect an "every man for himself" behavior. Instead, they recognize (?) there might be other competition, other sperm donors if you will, and they therefore co-operate so one of their own wins.

Does this mean monogamy is unnatural? Or at least at one point was not the norm? And still isn't? As why continue to optimize for co-operation?

One hypothesis is that the shape of the glans penis serves to push rival sperm out of the way and behind the glans to be scooped out of the vagina.

I wouldn't call monogamy unnatural. But it may be a more recent invention for humans. We still aren't sure how long it's been the norm.

It's possible that humans used to rape more often. It's also possible that humans practiced forms of polygamy. Either way, cooperative sperm makes sense. It's one of those things where a simple mutation would provide a clear benefit over the competition.

> What's different about sperm-cells is you would expect an "every man for himself"

You could expect that if each of them were an individual. Are they? One could say that all sperm-cells in a single ejaculation are part of the same single man.

Therefore the principle still holds, but it could be re-phrased as:

"Every sperm-cell for the donor-man"

All the other cells have the same DNA[1], they are like identical twins. It's like an army of clones.

Each sperm has a different DNA, they are like siblings. It's expected some cooperatio, but also some treason and backstabing.

[1] Ignoring some interesting cases.

> It's expected some cooperatio, but also some treason and backstabing.

That wouldn't be surprising, but I don't know if that is true.

I wouldn't not be surprised either way. A species survives not because its individuals do but because its genes do. Taking all available genes and spreading a subset of them amongst sperm-cells randomly is an interesting strategy.

It might be even optimal because the traits of a sperm-cell that make it survive during conception are not the same traits that help an individual thrive outside the womb.

If the 'fastest swimming' sperm-cell would always win, it would mean that in future generations faster and faster sperm-cells would win, but that would not necessarily help the survival of the species.

> I find myself wondering if there is a primitive consciousness on the cellular level

That seems to be obviously true to me. The alternative would be that consciousness simply appears at some point out of literally nowhere because there would be no lower levels from which it emerges.

Sounds like this

* pushes the problem one level down ("why are cells conscious?")

* adds the problem of explaining how consciousness of a person relates to consciousness of its cells.

What would this model help explain?

Right, but it seems that both problems are easier than "it just emerges out of nothing".

Cells consciousness would be a much, much simpler sort of consciousness, something any "object" that somehow is capable of searching for food and avoiding "danger" should possess.

Higher level things emerging from similar, but lower level things is not a mystery, it's something expected (like ant colonies).

I'm vaguely for pan-psychism as in, it sounds good but I haven't thought about it for even 5 minutes. But I'm more interested in the version where all matter has some kind of proto-consciousness. Still, no idea how it's suposed to work in detail: how can it make a difference whether a particle is part of an information-processing system? There is an infinitude of mappings between physical systems and mathematical functions (I'm probably plagiarizing a half-forgotten version of this https://joe-antognini.github.io/ml/consciousness )

I has to go all the way down by that logic, right?

> Conversely, when you look at the dynamics of large groups, organizations, and corporate entities (institutions as well as business, up to whole nations), it's hard not to see them as organisms in their own right that have a sort of meta-consciousness independent of their component humans.

That's actually a thing, or at least there's a name for it:

https://en.wikipedia.org/wiki/Egregore

This struck me like a Medicare benefits review commercial. I think those are also a bit more substantive. ;)

I don’t think there’s a consciousness but I think most biologist would agree there must be some kind of “awareness” within cells and imo likely that awareness is the basis for what we’d call consciousness.

I heard sex exists to reshuffle genes to make it difficult for parasites

I guess if your offspring has an entirely different body plan than you and it's only their offspring that resembles you then it would take a very clever parasite indeed to complete the cycle and follow the germ line across both transitions.

Parasites will often suppress the host's immune system. Reshuffling immune attack vectors should suffice.

If sperm cooperate, I wonder if the effects of the reported[1] historical decreasing sperm counts are worse than thought. For example, if the value drops by half, perhaps the decrease in fertility is not linear, but quadratic, falling to 1/4 of the original value, because each of the 50% left has only half the average number of peers to cooperate (this is only an example. I have no idea on how fertility scales with sperm counts).

[1] https://www.amazon.com/Count-Down-Threatening-Reproductive-D...

> About one-fifth of mammalian (including human) sperm are typically abnormal, containing no heads, two heads, two or more tails, oddly misshapen or malfunctioning tails, and so forth.

TIL

For myself, it was something like 94% misshapen. The fertility doc told me not to worry.

Indeed it was not an impediment.

You can get a microscope on Amazon for a few hundred bucks that lets you see this, red blood cells, and the critters that live in the water behind your house. Fun way to spend a weekend!

any specific recommendations that one could hook up to something to record the images/video?

Technically you can record with your phone through the eye piece.

It's no fun

there are some microscopes which are selling with a separate camera. microscope and camera spend you at least 6000$, then you can capture pictures on computer.

It's not as good as the devices built to take pictures or videos through microscopes (or microscopes that use them built in). It is a cheap and easy way that I've had success with.

Aliexpress /temu/ebay etc sell cheap eyepiece phone holders - not perfect, but makes my ex-schools microscope so much easier for my kids to use as we can a see the screen together.

I have an AMscope (without the ability to take images/video). I purchased it in 2014 so no promises on the brand today:

https://amscope.com/products/b120c-e3?gclid=Cj0KCQiAkeSsBhDU...

From my research into microscopes for fine electronics work, the keyword you are looking for is “trinocular”. They have standard camera mounts built in and you can attach almost any camera via an adapter.

https://www.youtube.com/@micro_safari has some recommendations (disclaimer: they do run a small shop, but he seems knowledgeable)

When we were dealing with fertility issues I started doing (somewhat) legit sperm counts at home. I was sick of paying hundreds of dollars each time.

I’m sure it wasn’t super accurate but it was accurate enough to know if things were improving on certain medications or not.

Isn’t the purpose whole “sperm race to the egg” thing to QA the sperm? Slow or immobile sperm is a proxy for manufacturing defects (which could affect the genetic material within, I suppose).

Wait until you realize almost four-fifths are dead, immotile or slow moving. Only around 5% are actually viable.

Time for Robin Baker to update the seminal "Sperm Wars" [1]

[1] https://en.wikipedia.org/wiki/Sperm_Wars

>seminal

I see what you did there.

Let’s do a seminar on it this semester in the seminary.

The idea that sperm cooperate is quite funny. They are sometimes used as a sort of example of how wildly competitive life is from the very start, we were in cooperation to even be born. In fact, it was a group project.

> example of how wildly competitive life is from the very start

Isnt sperm more like data rather than a living thing? Nonetheless, without cooperation, humans, would not have survived. It is only logical that our initial data carriers also cooperate in some way.

Yes, they are about security by redundancy, and randomization. Every child you have is different and therefore more able to survive as circumstances change.

I read a book long ago called Sperm Wars. It’s almost pornographic in style but every chapter describing the biology of sperm and sex is preceded with a fictional narrative of some courting ritual.

Really blew my mind at the time at how complex and interconnected the behavior of sperm and egg are with general human behaviors via hormone communication.

You should also read Dawkin’s The Selfish Gene.

Everything we think we are, and what we are here to do, is fight to make our kids or our kin’s kids (if we can’t / won’t reproduce) survive and do the same.

Politics, architecture, everything is you being manipulated to do this.

Oh yes that’s a great one too.

The general category of evolutionary biology humbles you quickly out of any notion that thinking you have anything resembling free will in most of your life.

I think stepgen gould (?) joked that taking that perspective, you could easily argue that the purpose of the human organism was for shit to make more shit.

Sincerely, there really is no meaning to life other than to make more life. Cancer is the extreme and absolute epitome of this.

Any other meanings we as humans might contrive from life are all just coping mechanisms from that brutally simple reality.

And that only because the kinds of life that (briefly) didn’t absolutely prioritize making more life are, almost by definition, extinct.

You postulate that evolutionary forces are the only source of meaning. But there is another point of view, stating that the only source of meaning is a human mind. Without an human observer there is no meaning at all.

If we go this road, then human mind is a byproduct of evolution that invented "meaning" and I see no obvious reason to subordinate it to evolution, which is a meaning created by a human mind to make sense of empirical data it got.

I can agree that other biological features of human body and of human mind serve to evolution, and it kinda subordinates our minds to evolution, and recursively it subordinates meaning. But I cannot fathom is it even possible to argue that all mind's traits are subordinated to evolution. There are things like schizophrenia that doesn't seem very good for evolution. Probanly there are better hidden traits, that may give our minds some freedom from evolution.

I don't think evolution creates or produces "meaning". It is just a blind dumb mechanism which occurs when things self-replicate.

Meaning is something in the human mind, related to language. Words and other actions have "meaning". We can ask "what is the meaning of this word, or of this action?". Meaning relates to communication between individuals, not to emergent phenomena like evolution.

And "kin" basically means anybody or anything that contains SOME of the same DNA.

>Everything we think we are, and what we are here to do, is fight to make our kids or our kin’s kids (if we can’t / won’t reproduce) survive and do the same.

IIRC, the point is that this is not the case - that's what our genes "want", with manipulations like sex feeling good to get us to have children (but we fought back with contraception, and evolution is extremely slow to catch up).

> When sperm disband their cooperativeness, it’s each pollywog for himself.

I'm surprised to see Nautilus implying that all sperm are male. Half of those pollywogs carry an X chromosome. You go, girls!

Some of this might not be accurate.

"Human testes are on average 0.06 percent of body weight and sperm concentration is about 25 million per ejaculate."

25 million per ejaculation would fall in the "low" fertility category. At the other end of the range you can have 10x that amount.

The part about bee phallus implantation is true, but to my knowledge it does not really deter others (in honey bees at least). The queen mates with multiple males and has offspring using genetics from more than one.

25 million is quite low. ~15 million per ml is considered infertile and you usually ejaculate at least 1.5ml.

That's because sperm-cells of a single male all share the same goal. They are not really competing are they? They all have the same goal, carrying on the genes of the same individual.

> When the hard-working little swimmers encounter the thicker vaginal mucus, their path is slowed. So the sperm often join together at their heads, which gives them greater swimming speed (up to 50 percent faster) than if they were to carry on individually.

Teamwork makes the cream work.

Well, they do all have pretty much the same dna, so it makes sense I suppose. The same way that ants cooperate.

> This pattern is consistent with data on the average number of male sex partners for females per birth: gorillas, one partner per birth; human beings, 1.1; baboons, 8; bonobos, 9; and common chimps, 13.

I don't understand this statistic. 'Human beings average 1.1 male sex partners per birth...' we need to see the data behind this. This isn't implying that 1 in every 11 children are bastards, no?

That number (1.1) seems low, considering the average number of lifetime sex partners for women is something like 5 or 6 and the average number of births (fertility rate) is something like 2. How can we track down the source for that statistic and figure out how it was measured?

This is one of the reasons that 23andme has warnings about dna matching to relatives

https://theconversation.com/what-are-the-chances-that-your-d...

> In certain bee species, the male’s body literally explodes after copulation, due to a sudden increase in intra-abdominal pressure, which embeds part of the now-deceased male’s body into the female’s genital tract, preventing other males from copulating with the just-fertilized female.

Wrong; other males can still mate with the female. The whole point is for her to mate with multiple males. I wonder what else in this story is incorrect

It says "in certain bee species". Are you an expert in the field? You seem very confident here that this doesn't apply to any bee species.

A citation might help your argument.

Since I was curious too, I dug up this:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1847503/#:~:tex...

Multiple males do mate with the queen, with the everted endophallus acting as a signal to other males and perhaps offering protection from the queen's stinger. Technical term seems to be "mating sign," and males prefer queens with a mating sign.

But there are 20,000 bee species, many of which are actually solitary. That just looks at the honey bee.

I can think of worse ways to die than a fatal orgasm.

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