Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How the placenta evolved from an ancient virus (2020)

whyy.org

Post reply on HN
Print view View original

91–100 of 130 posts

Re: How the placenta evolved from an ancient virus (2020)

#91

Post by MrVandemar »

TravisCooper wrote: post #55
MrVandemar wrote: post #27

Earlier quoted context omitted.

The eye evolved in much the same way, a bit at a time. It didn't just turn up one day. As for the virus/placenta thing, I recall reading a similar thing about wasps, though I couldn't provide any citations, that the method by which a wasp stops the immune system of a host (such as a catepiller) from attacking its eggs/larvae is viral in origin, and remarkably similar in some ways to the way a mother's body doesn't at…

Strange that an uncoordinated, random walk of mutations would keep a profound number of changes in tact, ready for some other random bit to take place and it all just "fall into place". The eye didn't evolve. Hearing didn't evolve. Smell didn't evolve. This line of thinking is just hopeful projections of desired causality.

> The eye didn't evolve. Hearing didn't evolve. Smell didn't evolve.

I don't know if you're being somehow pedantic for some definition of "eye" or "evolve", or if you're one of those "Intelligent Design" creeps.

Re: How the placenta evolved from an ancient virus (2020)

#92

Post by harshreality »

TravisCooper wrote: post #59
InSteady wrote: post #57

Earlier quoted context omitted.

>Which came first, the Heart, Blood Vessels or Blood? Which ones were "selected for" before the others arrived? How would a random process, uncoordinated through time select for these things and keep them while they're "not useful" until they are? etc etc Evolutionary biologists have very detailed answers to all of these questions, plus a bunch more that are far more complicated and confounding to laypeople. You can…

This is absolutely untrue. It's strange that an uncoordinated, random walk of mutations would keep a profound number of changes in tact, ready for some other random bit to take place and it all just "fall into place". The eye didn't evolve. Hearing didn't evolve. Smell didn't evolve. These explanations are always full of "must have" and "must have been". This line of thinking is just hopeful projections of desired ca…

Eyesight is just photon-sensing. There are primitive animals with primitive light/dark sensing.

Hearing is just vibration- and motion-sensing. It evolved from the lateral line in fish, which is not limited to "hearing" per se, but detects motion—current and transient pressure waves that might indicate predator or prey swimming nearby.

Smell is just chemical sensing. Catfish have chemoreceptors across their bodies.

A lot of intermediate forms are impossible to present to you as evidence because all we have is the fossil record which generally doesn't include soft tissue, which is where most of the interesting stuff happens.

One mutation that enables the slightest bit better sensing, provides an advantage, and offspring of that species in that area will gradually end up with that adaptation. Then it repeats. The "must have" is not dictated by some agent, but by environmental selective pressure, relative to pre-mutation versions of the same organism. It's induction, but for biology rather than math/cs.

It's quite possible that other types of photon and vibration and chemical sensing could have evolved, and would be superior, but we started down a path that locally descended to where we are now. And the existing tree of life would predate or out-compete pretty much any new multi-cellular life that tried to "experiment" and "evolve" novel sensing organs.

You want to talk about just-so stories? Cephalopod eyes attach to the optic nerve on the opposite (back) side of the retina, so they have no blind spot. Did a designer goof up on vertebrate eyes and not fix it, but instead implement a very complicated neurological fix involving saccades and "blinding" our brains to the instantaneous hole in our vision?

Re: How the placenta evolved from an ancient virus (2020)

#93

Post by jmyeet »

vlovich123 wrote: post #32
jmyeet wrote: post #28

Earlier quoted context omitted.

Here's another sobering thought: you represent an unbroken chain from the universal common ancestor of successful reproduction going back billions of years and probably trillions of generations (given that many of those were as a single-celled organism). Every one of those generations a success. So if you fail to reproduce you will break that billion year old chain of evolutionary success. Here's another: you have 2…

Humans are social animals. It’s myopic I think to only evaluate based on reproduction and genetic propagation. For example, most bees and ants are not involved in reproduction but they are all involved in helping the species survive into the future. So even if you don’t reproduce you have a critical role to play in society (helping it stay cohesive, helping productivity, helping through your work efforts, helping you…

This is a perfect example of what I like to call the Eggs-Waffles Phenomenon. Basically, you can’t say something like “I like waffles” on the internet without someone replying “how dare you malign people who like eggs”. And here there’s not even a value judgement or personal preference yet this has somehow been perceived as an attack on the childless. Others have jumped in to bemoan the perceived attack on the family. It’s wild.

Nowhere do I argue that you should or shouldn’t reproduce or that either outcome affects your perceived or actual value. The word “fail” seems to be doing a lot of heavy lifting in your perceptions here.

Re: How the placenta evolved from an ancient virus (2020)

#94

Post by JPLeRouzic »

overtomanu wrote: post #86
_0ffh wrote: post #85

Earlier quoted context omitted.

Here's another, superficially quite perplexing one: Your female ancestors vastly outnumber your male ancestors.

For those wondering, I think this is mostly because of men having multiple wives.

I don't understand that, IMO it's more than only high cast/class men could reproduce, others were used as slaves/living tools. Isn't the main change brought by the Neolithic?

Re: How the placenta evolved from an ancient virus (2020)

#95

Post by _0ffh »

JPLeRouzic wrote: post #94
overtomanu wrote: post #86

Earlier quoted context omitted.

For those wondering, I think this is mostly because of men having multiple wives.

I don't understand that, IMO it's more than only high cast/class men could reproduce, others were used as slaves/living tools. Isn't the main change brought by the Neolithic?

Imagine drawing your ancestry tree, parents, grandparents, etc. you will of course have as many male as female nodes. The higher variance of male reproductive success makes it likelier for two given male nodes to be filled by the same infividual, than for two given female nodes.

Ed. Of course this only works if some males have more than one reproductive partner over their life span. Serial monogamy, escapades, and polygynie are the obvious probable factors in skewing the symmetry. I might have missed some less obvious ones, but can't think of any right now.

Re: How the placenta evolved from an ancient virus (2020)

#97

Post by nkrisc »

TravisCooper wrote: post #47
zakki wrote: post #22

If every part of a human coming from evolution, how it synchronize between each part? Is there any books explaining evolution in detail? How cell formed? How they found a way to multiply? How they choose DNA to store the information? And so on.

[flagged]

[flagged]

Re: How the placenta evolved from an ancient virus (2020)

#99

Post by RangerScience »

TravisCooper wrote: post #47
zakki wrote: post #22

If every part of a human coming from evolution, how it synchronize between each part? Is there any books explaining evolution in detail? How cell formed? How they found a way to multiply? How they choose DNA to store the information? And so on.

[flagged]

When we design systems we seek to use (1) as few parts as we can with (2) as simple interactions between them as we can and (3) with as simple parts as we can. Cars, databases, folding chairs.

Emergent (evolved) systems use (to their benefit!) a great deal of interacting parts, with complex interactions, and with complex parts. Economies, ecologies, the Internet; to some degree, neural net AIs.

It’s possible to set aside the question of evolution vs creation, and just notice that these two categories exist, and we’re clearly in the latter.

Re: How the placenta evolved from an ancient virus (2020)

#100

Post by lynguist »

derac wrote: post #74
BurningFrog wrote: post #60

Earlier quoted context omitted.

Ants and bees in a hive have very similar genetics. Typically 75%, and sometimes 100%, if I remember. This means that a hive in some ways is best thought of as a single organization, which happens to have a "distributed" body. In that view, the non reproducing individuals are propagating their DNA in the same sense that human liver cells do, even though they don't have the direct involvement that down and egg cells d…

Human beings are 99.9% genetically similar to each other. Also, we're about 99% genetically similar to chimpanzees.

And 30% to a tomato. So what?

The basics of cellular respiration are always the same on this planet.

Post reply on HN