I sometimes give lectures on evolution and I usually open with this classic puzzle (due to Dawkins): most ants (and other social insects) are sterile. How is this possible? Why would evolution select for genes that produce sterile individuals? (You might want to see if you can figure this out before continuing.)
The answer is that ants are not organisms, they are organs. The ant colony is the organism. It just happens to be made of parts that are not physically connected to each other.
Well, it turns out that humans are much like ants in this regard. A single human individual cannot reproduce. Even a single fertile couple cannot successfully reproduce in the wild (if you doubt this, watch a few episodes of Naked and Afraid). The minimum viable reproductive unit for homo sapiens is a tribe or a village.
This sort of organizational grouping is found at all of the levels of abstraction in life. Even your DNA is not really a unified whole, it's a bunch of genes that have glommed together in a cooperative effort to reproduce themselves, but it's not an organized or homogeneous effort. That's why you have freeloaders ("junk DNA") and defectors (cancer genes) who put their own interests above those of the group. What happens at the cellular and molecular level is really not so different from what happens in human societies. The presence of brains changes the dynamic, but not in any fundamental way. At the end of the day, it's all just self-replicating information looking for an ecological niche and a reproductive edge. The idea that human individuals are somehow special in this process is mostly a prejudice brought on by our particular point of view, namely, the fact that our thoughts reside in brains that are strongly bound to bodies. The ability to see beyond onesself can be both powerful and humbling.
>Even a single fertile couple cannot successfully reproduce in the wild (if you doubt this, watch a few episodes of Naked and Afraid). The minimum viable reproductive unit for homo sapiens is a tribe or a village.
Do you have evidence for this that's not a reality TV show?
Edit: I have found the Lykov family who had two children in isolation; they did already have two children who would have been 13 and 6 at the time of the third child's birth in isolation.
https://en.wikipedia.org/wiki/Lykov_family
> Do you have evidence for this that's not a reality TV show?
Yes. Let's start with the fact that there are no recorded instances of an isolated human couple successfully reproducing in the wild ever. Merely having a baby doesn't count. To be a viable evolutionary strategy you have to raise that baby to maturity and then that baby has to reproduce themselves.
In fact, this is not unique to humans. It's true of all simians. In fact, it's true for the vast majority of mammals. The only exceptions I can think of are some species of cats: leopards, cheetahs, tigers, mountain lions.
We can also reason from first principles: you need a minimum viable population in order to maintain genetic diversity. So even if it were possible for isolated human couples to reproduce, you'd need more than one instance of this, and these families would somehow have to find each other in order to procure mates. How are they going to do that?
Don't mistake modern density for a requirement. It's hard to find instances of anyone living alone for long periods, but that likely changes as you go back and there where fewer people and those people where more able to survive in the wild.
I remember going into back country with some friends as a teen, miles into 'the middle of nowhere'. Second day camping I see someone run by in yoga pants pushing a stroller as it turns out we where about 300 feet from a ski trail and people would run down the mountain in the summer for fun.
Well the holes in your arguments are deeper than that. A viable strategy need not be the only or even the optimal strategy.
If couple has kids and those kids find someone in a local tribe then both tribes and lone families would have worked. In effect you are trying to redefine his argument not just in terms of recorded history but also both couples not an individual one.
> If couple has kids and those kids find someone in a local tribe then both tribes and lone families would have worked.
You're attacking a straw man. Of course a couple can reproduce if they are in proximity to a tribe. But that still requires a tribe. It is a couple in isolation that is not viable.
The couple are irrelevant at that point. People can travel ~10,000 miles a year on foot. The fact their kids leave in no way impacts them being in isolation. Heck, someone can know where other people are and still be isolated.
I rarely see people on HN miss the point quite this badly. Reddit, yes, but not here.
The point is: for your scenario to play out, a tribe has to exist (and it has to be close enough for the couple's offspring to find it, but that's a detail). No tribe, no viable reproduction. Hence, the tribe is the minimum viable unit, even if it also occasionally supports an isolated couple somewhere in the vicinity.
Your argument is only true in the trivial sense that sexually reproducing organisms are only viable in larger numbers than a single pair; but that's a distinction that doesn't demarcate anything interesting. Humans are like ants, you say, but your argument also leads to the same conclusion about tigers, bears and other solitary animals in that they need more than a breeding pair to be viable. It descends into tautology.
Yes, humans are somewhat like ants in that they are usually social. Humans are adaptable enough to survive in pairs, though lack of specialization means they won't necessarily live the most comfortable life, so it would be an unusual choice. But there's nothing elective about ants' socialism. So in the end I don't think your argument works.
> your argument also leads to the same conclusion about tigers, bears and other solitary animals in that they need more than a breeding pair to be viable
No. Those species have specialized adaptations that allow them to live in isolation, which humans lack. And it's not just humans. All simians lack these adaptations. Indeed, the vast majority (perhaps all -- I can't think of a single counterexample) of non-carnivore mammals lack them.
Isolation does not mean other groups don't exist. It means lack of contact, and the adults don't need contact and as I have said children can move as happens with many territorial animals.
Ever heard of bears? I don't believe any of them have something that could be called a tribe (unless you redefine any form of family to be one). They simply don't have a source of food that could sustain any nontrivial population in small territory.
Even living alone most of there lives wouldn't stop them from finding a mate and having an offspring.
The OP isn't making absolute points, this is the point. An ant isn't really an organ, at least using normal word meanings. He means that it is effectively an organ, from a reproductive perspective.
People obviously are viable reproductive organisms in a technical/literal sense. But... the way people (and our nearest cousins) actually reproduce is in couples within a tribe/village/troop. People are evolved to reproduce this way and people evolved by reproducing this way.
For Lisper's overall claim to be valid, you only need the weaker result that an isolated couple's expected number of children living to adulthood is less than 2.
I understand. In fact, classifying individual social insects as organs doesn't sit well with me also, it feels more like philosophy than biology. I think it also ignores other possibilities that could explain why sexual reproduction is reserved to a subset of a population, but well, I don't teach evolution.
I don't know what evidence you'd want. The claim seems self-evidently true to me.
You were able to find one wiki article on a curious case of a family who, unlike billions of other people, survived as individuals for less than 50 years in partial isolation. That's impressive, but it doesn't change the basic facts of human survival.
Case in point, in the first paragraph of the link you provided about the Lykovs, the article says only one daughter yet survives (as of 1988, so they are probably all gone now).
Minimum viable populations are partially about day to day survival and team work, but in the long term it's about genetic diversity which is critical for long-term population survival. Evidence: all of biology?
Abakan Range is rather difficult place to live which is why they where left alone and the family was not from a culture of nomads. Yet, Agafia made it to 70 and is still alive.
That suggests it's far more viable than you might think. It's just more attractive places to live currently have people living there. Opportunity's for solitude where far greater when global population was lower, but it's unlikely for such things to enter written history.
Me too. Although I thought what he was going to say is the limited genepool would make grandchildren impossible (well nearly...) and generations after that impossible.
People are asking for citations to actual literature that support your claim that a pair of fertile people can't reproduce. I think what you're actually saying is that you can't bootstrap a viable population from a pair of people (which is definitely true from a population bottleneck point of view), but I think you're massively overstating your case. It would really help if you could point to some modern well-accepted textbook or paper that supports your claim.
Computational biologists, specifically those who utilize network models, are hoping to make this idea more concrete. It's well-known now that some real-world (including biological) networks are scale-free (mathematically, their degree distribution follows a power law). As an example, many gene networks have "hub" genes, that are related to several genes, whereas the median connectivity of a gene is fairly low.
Separately but also related, there's a growing sentiment that biological networks are self-similar - higher-level network-modeled abstractions are in fact topologically similar to lower-level subnetworks. This analogy may seem almost Hofstadter-esque at this point, but in a few years, who knows...
One of my favorite creatures in all the world is the lowly Trichoplax:
> Trichoplax adhaerens is the only extant representative of phylum Placozoa, which is a basal group of multicellular animals (metazoa). Trichoplax are very flat organisms around a millimetre in diameter, lacking any organs or internal structures. They have two cellular layers: the top epitheloid layer is made of ciliated "cover cells" flattened toward the outside of the organism, and the bottom layer is made up of cylinder cells that possess cilia used in locomotion, and gland cells that lack cilia. Between these layers is the fibre syncytium, a liquid-filled cavity strutted open by star-like fibres.
I like these creatures because they are on the cusp of multicellularity: you can force them through a sieve that separates their cells which will then crawl around independently and try to reform the organism. You can dye two trichoplax different colors, force them through the sieve, and the cells will mix and form piebald organisms. So, they're like tribes of cells (IMHO.)
> This sort of organizational grouping is found at all of the levels of abstraction in life. Even your DNA is not really a unified whole, it's a bunch of genes that have glommed together in a cooperative effort to reproduce themselves, but it's not an organized or homogeneous effort. That's why you have freeloaders (which are called "junk DNA") and defectors (cancer) who put their own interests above those of the group. What happens at the cellular and molecular level is really not so different from what happens in human societies. The presence of brains changes the dynamic, but not in any fundamental way. At the end of the day, it's all just self-replicating information looking for an ecological niche and a reproductive edge. The idea that human individuals are somehow special in this process is mostly a prejudice brought on by our particular point of view, namely, the fact that our thoughts reside in brains that are strongly bound to bodies. The ability to see beyond onesself can be both powerful and humbling.
What happens at the cellular and molecular level is really not so different from what happens in human societies.
I am not quite sure to what extent you mean this. I would add that the bottle neck on evolutionary futures for our genes imposed by our reproductive system is very strong, and that there is no obvious analogy in societies. The existence of such a strong bottleneck of course shifts the game theoretical dynamics of cooperation and defection, strongly enabling cooperation between somatic cells (as you say, with cancer as an exception).
Interesting question: indeed why would evolution select for genes that produce sterile individuals (for ants)? What is the selection pressure ensuring only the queen reproduces?
Firstly, the drones creating offspring would lead firstly into a population explosion followed by a population collapse after viable and attainable nutrition sources nearby have been depleted. Once the population collapses to low enough numbers, even cannibalism does not work anymore and eventually that genetic line dies out.
Also, it is presumable there would be fighting over resources, and maybe multiple genetic makeups within a single nest also opens up the door for attacks from other nests, since detecting who is a friend and who is not could be difficult, making the nest (and its genetic makeup) vulnerable.
Also, the minimum reproductive unit for a mobile homo sapiens is obviously a man and a woman. But is it viable, too? I say yes. Their offspring can wander out away from their parents and find another isolated offspring that is fsr enough genetically, and create progeny and repeat the process. If the humans are somehow not mobile, then a larger group ("tribe") is needed to avoid inbreeding with its detrimental effects.
Your exposition of Dawkins' ideas is neat, and probably helpful to people in an introductory biology course. I'd like to help clarify some of your comments on the genome.
> Even your DNA is not really a unified whole, it's a bunch of genes that have glommed together in a cooperative effort to reproduce themselves, but it's not an organized or homogeneous effort. That's why you have freeloaders ("junk DNA") and defectors (cancer genes) who put their own interests above those of the group.
"Cancer genes" don't exist in the sense that there aren't genes that specifically cause cancer. If there were then every individual with a full gene complement would get cancer. What you're referring to are certain alleles that can arise which change cellular processes so as to break cooperative patterning of cell behavior. If you're lecturing in evolution it might be nice to use a technically correct description to match the Dawkinsian semantic splicing you're resting on :) Call them "oncogenic alleles" instead.
"Junk DNA" is a blind concept that conflates sequence complexity with function. The argument goes that these pieces of DNA are just copies of each other and serve no obvious purpose, thus they are junk that "freeloads" off their host. This ignores the fact that these elements exist in virtually all complex organisms, and have lineages that last tens or hundreds of millions of years, which is longer than the lifespan of most species. If they were only an energetic drag on their host they would be selected out over these time scales. Instead, they appear to serve important purposes in genomes. There is a huge amount of evidence that this "junk" is also an "organ" of the genome that provides essential function in an evolutionary sense. This perspective is old, more than 30 years, and the first reference to it I'm aware of is from a study in 1983 that showed that Escherichia coli with transposons evolved faster than those without: https://www.nature.com/articles/303633a0
Can you recommend any good books about genetics and natural selection to people who don't have a biology background? I can handle some math, but I just break software for a living and I don't know biology.
Sorry for the sidetrack, but thanks for posting this. I've always wondered about some of the higher order implications of natural selection, and ants are a great example. Like how megacolonies take in ants from other places, that's so crazy because it doesn't make sense once you're looking at a small enough perspective but makes perfect sense at a larger scale. Bees are cool too.
This is not a puzzle, and your answer is not a solution. It's formally wrong in terms of actual biology. Another way to think of it is as a narrative that attempts to explain- but it isn't a particularly useful one. It's not a "right/wrong" (and it's not something people can "figure out").
That some members of a population are sterile doesn't require you to completely rearrange your definition of biology, speceis, and organism.
> The answer is that ants are not organisms, they are organs. The ant colony is the organism.
I am confused by this, because this seems to be the "group selection" idea that is vociferously rebutted by Dawkins and others.
It is really not clear to me what the bright line is between group selection and kin selection. If social groups are genetically similar (which is most often the case in nature and human society), group selection and kin selection appear to be equivalent.
To really answer this you should read "The Selfish Gene." But the TL;DR is that the unit of selection in Darwinian evolution is neither the organism nor the group, but the gene. Ant colonies are the phenotype of a group of genes that glommed together over the years to form an evolutionarily viable unit. But the unit is not what is being selected ever, it's the individual genes. The phenotype of a gene is not necessarily constrained by any physical boundaries. (For example, the phenotype of the human genome extends into outer space!)
> To really answer this you should read "The Selfish Gene."
I did. Well the first several chapters at least. I did not find a convincing answer to the question I am raising here.
> The phenotype of a gene is not necessarily constrained by any physical boundaries.
Sure it's not necessarily constrained. But in practice there is very high correlation between family relatedness and physical proximity / social group.
If the main rebuttal against group selection is "families can be spread out", I don't think that warrants the level of criticism that is leveled at it. An organism surrounded by genetically unrelated peers is the exception, not the rule.
EDIT: Reading a bit more, I think I may be understanding this distinction better. "Kin selection" and "group selection" are more different than the names suggest. "Kin selection" means that natural selection incentivizes an individual to be altrustic towards their own kin. "Group selection" means that natural selection will favor the survival of an entire group over another group based on the comparative genetic strengths of the two groups.
Huh, this makes me think, culture is like artificial selection. Some “organisms” have evolved to live off of the land, and others evolved to live off of other humans!
Yes, obviously.
But I am honestly baffled here. I mean, when did anyone really seriously argue otherwise? Isn't that already universal knowledge what you are describing here?
(Well, depends a bit on the definitions, I'd still say that ants are organisms, but so is the ant colony, and yes, you always have to see the bigger picture)
I don't get what the NYT is trying to achieve with their "reporting" here.
(BTW, the title here on HN has been changed, for anyone coming a bit later to these comment threads)
> Isn't that already universal knowledge what you are describing here?
Not only is it not universal knowledge, there are substantial cohorts of people who will vehemently deny that it is true. In fact, there are people asking for additional evidence in other branches of this very discussion!
I found that spending a bit of time visualizing the scale and complexity of cells is helpful for not finding this sort of messiness surprising. A similar thing that used to surprising me was the idea that some viruses, like herpes simplex, hide out inside cells for years and years.
The complexity insides eukaryotic cells is startling, and compared to individual molecules they are massive. (Prokaryotic cells are 0.1 - 5 microns, while eukaryotic ones are 10-100 microns. That means eukaryotic cells are larger in volume by 2-9 orders of magnitude! It also lowers the impressiveness of comparisons between the number of gut bacteria cells and human cells.) If you think of each cell as a person, then the body is an army of 30 trillion soldiers each with his own copy of instructions to follow (which he copied from someone else) and many possible ways to get hurt or die. It's not so surprising that some fractions of the soldiers will have very small errors in their copy of the instructions, which they will pass on as copies to other soldiers, or that individuals could get a tape worm and still fight.
You might like my crufty and slowwwly-loading page http://www.clarifyscience.info/part/Atoms for "nanoview" (zoom so that 1 nm looks like 1 mm). And http://bionumbers.hms.harvard.edu/ to look up biological numbers. So cells are zoomed to large garbage bags, rooms and buildings, proteins[1] look like bits of Play-Doh, and atoms like sand.[2]
Yes, the thermodynamics alone are vastly different between an Elephant and a mouse, let alone between an Elephant and a bacterium. We are somewhat fortunate that life can exist across such vast scales, as it really gives us a lot of things to study and think about.
I meant the scale range when considering the constituent components of any given biological organism:
Let's say we take the hardware basis -- cpu, instruction sets, registers, buses, etc. -- as the 'organic chemistry' analogue -- the substrate. Just the basic cell, which is a profoundly amazing machine, would require layer upon layer of software. By the time we reach the level of an 'organ' or 'system' along the biological model, it would be a monster.
We humans, for example, have apparently (per my search engine) somewhere between 10^13 to 10^14 cells. That's 4 to 5 orders of magnitude larger than the total number of computers on this planet.
I'm amazed at how much we still don't know about our human body. Engineering in other areas, like computer sciences, is much easier because we understand the fundamental concept behind it. But in bioengineering or pharmacy, a lot of them are trial and error, and serendipity, because I think we simply don't really understand how the cell actually work in details yet. [0]
I came from physics into bio. I was one of those arrogant physicists that though the bio majors were just not 'smart' enough and couldn't hack it in math, so they fell into bio. Maybe that was true of some of my fellow students, but as a field, bio is just insane. I was terribly wrong to think those things.
Bio is crazy complex. We've been poking the brain for a century now, and we have basically gotten no-where. At least we know that now. Take astrocytes/glia as a tiny example. These are the 'glue' cells in a brain that hold and feed the neurons. Sure, they do that, but a lot of new research is saying that they help modulate the synapse as well, the fundamental thing that makes thinking happen. Maybe. We basically have no idea now. We can't even say how many astrocytes there are in a typical brain. Is it 50%, is it 10%? Each new study overturns the last. It's chaos. What even is a synapse? We have no idea. Multiply this over every tissue in a body. And then that's only humans, let alone turtles and birds and bacteria and viruses etc.
One must always remember that bio was 'designed' by a very drunk, very horny, illiterate schizophrenic over 4.5 billion years with an average design cycle of about 22 minutes (~10E14 total cycles). It makes no sense because it never did.
> Optogenetics is a biological technique which involves the use of light to control cells in living tissue, typically neurons, that have been genetically modified to express light-sensitive ion channels. It is a neuromodulation method that uses a combination of techniques from optics and genetics to control and monitor the activities of individual neurons in living tissue—even within freely-moving animals—and to precisely measure these manipulation effects in real-time.
Exactly. I think he was missing my point: Cells and biological structures of that size have always been easy to look at, it's not so easy to do the same with smaller structures, like DNA.
Yeah, with DNA, you literally have to x-ray it to 'see' anything. That tends to be rather destructive. And as science goes along, we are seeing that the smaller stuff is really really important, like scaffolding proteins in synapses.
The article doesn't touch on X-chromosome Inactivation[1] which makes all female animals mosaic. Though in the specific case in the article SCN5A isn't on the X[2].
X-chromosome inactivation is a type of an epigenetic change. It is one of many that happen throughout the body - I would say there are very few cells in our bodies that have the same epigenetic markup. We've known about this for a while.
The article discusses genetic post-meiotic changes that propagate differentially through the body. We knew it happened for a while now too, but it was always presented as a curiosity or an anomaly. We are now learning that it is much more common than we anticipated. Like presented in the article, it might actually explain some clinical phenotypes as well.
"Secondly, the fraternal birth order effect operates through a biological mechanism during prenatal life, not during childhood or adolescence. Direct evidence for this is the fact that the fraternal birth order effect has been found even in males not raised with their biological brothers – it has been determined that biological brothers increase the odds of homosexuality in later-born males even if they were reared in different households, whereas non-biological siblings, such as step-brothers or adopted brothers, have no effect on male sexual orientation."
That is consistency with a "kin-selection" theory of homosexuality, that within a family, evolutionary factors favor having partially non-reproductive members in a family (perhaps because in a family with two males, on average, the total reproductive fitness is greater where there is one father and one uncle, not two fathers)
The math is pretty clear: the chances that homosexuality, as a trait in and of itself, is selected for is highly unlikely. A gay person would have to result in their siblings having 2x as many children as they would have themselves, which is possible, but a really steep hill to climb. The explanation that makes much more sense to me is that homosexuality is an occasional side effect of something else which is highly adaptive to non-gay siblings who possess it.
You are assuming that for beneficial genes to pass on, it must result in an 2x number of children per generation. That assumption is false, even a 1.1x increase in children can be compounded. Also, imagine if there was a severe bottleneck event in the human population, where sub-populations with homosexuals had a much better chance of survival.
Furthermore, what math is so "clear", that you completely gloss over it?
> A gay person would have to result in their siblings having 2x as many children
Should have been:
> A gay person would have to result in their siblings having 2x as many additional children
Here's the math:
An individual's children have 50% of their genes. Their nieces and nephews share 25% of their genes. Therefore, if the hypothesis is that homosexuality evolved to promote the production of nieces and nephews at the expense of producing direct offspring, this adaptation would need to result in at least two nieces/nephews for each offspring that the homosexual individual would have produced directly.
So, if we assume a stable population where each couple produces 2 offspring, a gay person would be giving up producing 2 of their own children. In order for this strategy to break even, it would have to result in their siblings producing 4 offspring, in addition to the offspring that they would have had anyway.
Possible, but not likely.
On top of the math just being heavily stacked against this being an explanation, there are other reasons why it is unlikely:
1. If this were a successful strategy, you would expect to see a much higher prevalence of gay people than we currently do (<5% of the population).
2. There are already adults who take on this hypothetical role of assistant to the breeders: grandmothers. And they avoid the fertility tradeoff because they are evolved to stop being fertile at a certain point in their lives.
Humans have many traits that seem to support survival at the tribal level, and having a spectrum of homosexual and heterosexual individuals could well have supported child rearing or reduced divisive competition. Just look at bonobos.
See my reply to rubatuga. If the genetic math doesn't work out for helping raise your sibling's children vs. having children of your own, it absolutely doesn't work for raising the tribe's children (who are less related to you than your sibling's children) vs. having your own.
I think you missed my point. If survival of human groups generally occurred at the tribal level, i.e. either a tribe successfully cooperated and survived or suffered excessive discord and died out unless they were adopted by a different tribe, the benefits would not rely just on direct actions within an atomic family unit. The group had to have enough genetic diversity, or invite enough in, to prevent disease from inbreeding but generally most of the tribe would be somewhat related. The "math" surrounding just caring about whoever has 1/2 or 1/4 of one's genetic material may not be as important as the survival of the larger cooperative group. All of those little selfish increments might not matter if isolated, catastrophic group collapse rendered them nil. I think you are trying to over-simplify the scenario. Other traits point to increased cooperation being crucial, such as the idea that concealed ovulation attenuated direct male competition during fertile periods. Even in The Selfish Gene, Dawkins describes game theory situations where certain ratios of populations are stable, like the simplified hawks versus doves. In the same way, there may have been a stable ratio of homosexual tendencies or sexual flexibility that acted as a cooperative buffer, as they would assist in child rearing in the same way that you mention grandmothers. Trying to boil it down to just grandmothers because they might have the largest genetic "interest" is overly reductionist. It's not just an addition problem. And bonobos are a great example of all with all sexual bonding being very close to us genetically. Who's to say that our cultural notions of what homosexuality entails translates across to thousands of years of pre-historical culture?
You're not wrong, it's a mixture of epigenetic changes, and local environment changes. As a cell differentiates, it definitely changes its epigenome. These changes are also mediated by cell-cell interactions, and other morphogenic proteins, for example, the SHH gene:
https://en.wikipedia.org/wiki/Sonic_hedgehog
Nitpicking: We have the XY system but birds have the ZW system where the male birds have the chromosomes ZZ and the female birds have the chromosomes ZW (More info:
https://en.wikipedia.org/wiki/Sex-determination_system )
I still can't find out if in this case the male birds have a random inactive Z and are mosaic. I guess that there is something similar, but I'm not sure.
Thanks, I was just lifting that from the wiki article (arthropods are animals too, and they don't have XY chromosomes either, of course). Those crazy feathered therapods! Plus, nucleated red blood cells[1].
I'm surprised the article didn't mention immune system mosaicism, where populations of immune cells have mutations that allow them to look for different proteins. And I've heard a neuroscientist speculate that the reason there is so much brain mosaicism is to allow different neurons to express different surface proteins and allow them to recognize and avoid attaching to themselves.
Does this effect or render incomplete the results people get from services like 23 And Me? The doctor treating the baby had to do multiple DNA tests to verify the mosaicness, and was only able to determine the 5%/12% bad cells in the heart right/left after it was removed.
It definitely changes a few gene results. An interesting and related topic to mosaicism is chimerism, where in the case of Lydia Fairchild, she was told her daughter wasn't hers because of different DNA populations in the mother's body.
I mean, I would think that it's not so much external factors influencing your genes directly, per se. But certain genes being called into play and others not.
Or is - likely? - a combo of both? That is internal genetic variance, as well as the ability to be influences by external factors. It would seem, the latter would be the ideal, the most flexible / advantageous.
I'm looking forward to everyone understanding this. In the field, we've known that somatic mosaicism is important for decades. (And there was the bombshell somatic retrotransposition within the brain discovery back in 2011 [1]) that showed that more active rearrangements were happening.) But public understanding of scientific issues takes time. I think they're starting to know that sexual orientation and transgender identity are driven by biochemical processes, and that took decades as well.
Nope, downvotes can be for many reasons, disagreement is not required to downvote. (I often downvote comments that I agree with and find non-useful in context, and upvote comments I disagree with but which contribute to productive discussion.)
You seemed to be implying magic by arguing against crime being caused by biochemical processes in the brain. As far as we know all human behavior ultimately boils down to stuff in happening in the brain and the brain is a biochemical machine.
That's quite a stretch to say that I would imply something like that.. You should read the original comment again. To which I was simply writing a reply.
I don't know, maybe you should have a talk with some post-structuralists, or with some other folks who seem to believe that xyz is a "social construct"..
I just extrapolated a bit too unconstrained maybe.
Okay, you can accuse me of erecting a straw man now.
But the thing is, I don't know how many times I've seen this (or very similar) debates unfold. Definitely getting a bit tired of it, to be honest. So I just though, why not skip ahead a bit, leave out some of the usual steps, you know?
no, that would be a different topic (although prisons are probably not the best way to introduce socially beneficial patterns into human mind, quite the opposite).
Whether or not you like the implications behind something doesn't make it less true. There is a book called 'Behave' written by Robert Sapolsky which lays out that human behavior is determined by the configuration of your brain, hormone levels, culture, the environment you were raised in, etc (basically all things over which you have no control).
For example, if you have an underdeveloped prefrontal cortex then you are going to be more impulsive and have a hard time delaying gratification. These people are way more susceptible to committing crimes and it is purely down to bad luck that they weren't born with the right genes (or had some sort of injury that damaged their PFC). Another example is if you have a smaller amygdala, you're going to have a higher pain tolerance and experience less fear than someone with a normal sized amygdala. Again, this can change your behavior quite a bit as you won't be able to relate to what the average person experiences when they are in pain. These people will have less moral compass than others.
With those things in mind, Sapolsky agrees that if an individual poses a threat to others, we should still lock them in prison for the good of society. But the more we understand what leads to human behavior, the more we're going to realize how many things are out of our control (almost all of it).
I'm not sure I follow what your argument is here? Just for your information, Robert Sapolsky is a neuroendocrinologist from Stanford who has been studying this exact subject for the past 4 decades. The book agrees with your point that looking for a single reason to explain human behavior is impossible and a lot of things contribute (hence why he covers so many determinants of behavior, such as what is going on in your brain, your genes, what is going on with your hormones, where you were born, how you were raised, etc).
I don't see why the nature vs nurture debate is stupid or why how old it is matters? Clearly both things determine human behavior. The main point to be made in Sapolskys book is that almost all determinants of your behavior are out of your control. You don't choose which country you're born in, what genes you have, whether your brain develops properly, whether your parents are kind people or terrible people, what neighborhood you grow up in, what race or gender you are. Perhaps you should read Sapolskys book.
I don't see how that follows. Just because things can be explained by biochemical processes doesn't absolve anyone of responsibility. Even if you assume a person's behavior is completely deterministic, without any free will at all, holding someone responsible for their actions is still the right thing to do. It might change how we should treat those individuals, of course, but it isn't a get-out-of-jail-free card.
Do you mean that there's a biochemical "gene" (or similar) for behaving contrary to whatever someone believes is morally correct? Or that morality is an objective state?
They (downvoters) fail to realize that they are shooting the messengers, nothing more. But smart people understand. They know and will never cease to keeping them honest..
sometimes people asking leading questions that are a bit... let's say tired, aren't all that interesting. if there is a point to be made, they should just make it.
"smart people" (as you say) sometimes prefer forthright discussion.
Yeah, thanks. I am only trying to hint at the possibility that there are other avenues to consider than a simple "crime gene", ie. the answer is probably not as simple as the poster wants.
Genetics and the human body have proven to be increasingly complex.
Wait, what? When I posted this article an hour ago I did so with the exact headline used in the New York Times: "Every Cell in Your Body Has the Same DNA. Except It Doesn’t." Now it's got a new title (here, not in the Times). What gives? Who did this?
You know, at first I said WTF? — but you are right. Frankly, I've noticed the Times is increasingly resorting to headlines that wouldn't be out of place in USA Today or the Daily Mail. :-)
Can someone explain the grammar behind the title? It feels wrong, but the fact that it presumably passed NYT's copyediting leads me to believe it is correct.
What's the "it" referring to in the title?
The body? But the body itself has no DNA to properly speak of.
A single cell? That is not what the article is saying.
Trying to use the same construct for a different sentence:
"Every person in this room should have worn a suit. Except he didn't" -> a single person in the room didn't wear a suit, and I am probably looking at him while saying this.
"Every person in this room should have worn a suit. Except they didn't" -> there are several people in the room who didn't wear a suit, this feels closer to the meaning of the piece's title?
The "it" does indeed refer to "a cell"; the second sentence is like saying, "except (some particular cell) doesn't (have the same DNA as all the others."
If this (kinda silly) format is to be kept, a better headline is, "All the Cells in Your BOdy Have the same DNA. Except They Don't."
An even better headline is one that is sans the clickbaity style - just "Cells in the Human Body Don't All Have the Same DNA."
I think "it" is the body. If I sit at stare at it and think too hard about it then it feels wrong. But my brain made it work, almost liked it the way it is when I read it at first. It sounds like how the young people talk, which is to say not quite right but we are smart so we can figure it out.
The answer is that ants are not organisms, they are organs. The ant colony is the organism. It just happens to be made of parts that are not physically connected to each other.
Well, it turns out that humans are much like ants in this regard. A single human individual cannot reproduce. Even a single fertile couple cannot successfully reproduce in the wild (if you doubt this, watch a few episodes of Naked and Afraid). The minimum viable reproductive unit for homo sapiens is a tribe or a village.
This sort of organizational grouping is found at all of the levels of abstraction in life. Even your DNA is not really a unified whole, it's a bunch of genes that have glommed together in a cooperative effort to reproduce themselves, but it's not an organized or homogeneous effort. That's why you have freeloaders ("junk DNA") and defectors (cancer genes) who put their own interests above those of the group. What happens at the cellular and molecular level is really not so different from what happens in human societies. The presence of brains changes the dynamic, but not in any fundamental way. At the end of the day, it's all just self-replicating information looking for an ecological niche and a reproductive edge. The idea that human individuals are somehow special in this process is mostly a prejudice brought on by our particular point of view, namely, the fact that our thoughts reside in brains that are strongly bound to bodies. The ability to see beyond onesself can be both powerful and humbling.