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Sex determination NOT due to external/environmental factors, then?

In which animals is sex determination based on food availability? And as a side question: In which animals is sex determination based on the presence of predators? Let me elaborate on both questions. Females of the common reed frog have shown to exhibit a sex change, which is thought to occur...

[Mentor Note -- Merged accidental double-thread-start] In which animals is sex determination based on either food availability. Females of the Common reed frog have shown to exhibit a sex change, which is thought to occur due to low male density in the environment, so that's not quite what I...

@BillTre Thanks, but to make matters even more complicated: "Recent data have shown that the distinction between embryonic and extraembryonic endoderm is not as strict as previously thought due to the integration, and not the displacement, of the visceral endoderm into the definitive embryonic...

I'm getting contrasting information from different sources about the relationship between the hypoblast (one of the two structures that make up the inner call mass) and the endoderm (which will form a few days later on, after gastrulation, and which will eventually give rise to the GI tract and...

For my question it's irrelevant, because I'm interested in the relationship between adrenalin and melanin, which both have tyrosine and dopamine as their precursors. What exactly happens in between, such as different enzymes that are involved, that doesn't change the starting material or end...

Tyrosine -> Dopamine -> Melanin Tyrosine -> Dopamine -> Adrenaline How is this not the same pathway? That's irrelevant, it has nothing to do with the pathway itself. Interesting stuff, but I'm not talking about this gene. Your remark is comparable to the notion that vitamin D has also...

Do you have anything to support your 'no'? I've already provided two papers to support my 'yes'. Let me add a third one: "Catecholamines were first shown to play a role in pigmentation in nonmammalian tissues, especially amphibian chromatophores where both α- and β-adrenergic receptors are...

OK, thanks! What about you, @jim mcnamara, is a black skin related to melanin's relation with adrenaline? Yes/no.

White spotting in domesticated animals is not the same phenomenon as albinism. It may have the same phenotypic effect, but that's due to a very different genotypic alterations. So in reference to my question, this is not relevant information. That's why you possesses some adrenaline, but not a...

Why is it generally accepted that black skin is only caused by melanin, due to the intensity of UV radiation, in order to protect the body from skin cancer to develop? Because melanin is also, together with adrenaline, linked to the precursor: dopamine, thus both chemicals share the same pathway...

I've done some research, and found out that there is currently indeed no scientific consensus regarding this subject. In the 2016 book 'Epigenetics, Energy Balance, and Cancer', it reads: "Seminal work of multiple generations of humans in Sweden shows that food availability during prepuberty...

Glucocorticoids travel throughout the bloodstream all around the body, but they affect only the gene expression in hippocampus, it says. Not that gene/receptor in all cells. But still, if I misinterpreted that part, and it affects the expression of that particular gene in all cells, even the...

But those processes still affect the germ line cells. Take the maternally transmitted responses to stress in rats example I gave. Alterations are made to the glucocorticoid receptor gene in the hippocampus of the rat pup due to stress, but when this rat pup becomes an adult it can transmit...

I wasn't quoting a reputable biologist, but @BillTre, one of the Science Advisors on this forum, who in this topic said: and This wasn't a discussion about the exact same subject, but this clearly sounds like every biological process of inheritance involves natural selection. So in the last...

Epigenetics is not Lamarckianism. I'm only pointing out that natural selection isn't the only driver of genetic variation. But I don't understand how changes in somatic cells can have effect on the germ line. Do you?

Mammals go through two rounds of epigenetic "reprogramming" -- once after fertilization and again during the formation of gametes (sex cells) -- in which most of the chemical tags are https://www.realclearscience.com/blog/2014/03/end_the_hype_over_epigenetics__lamarckian_evolution.html. The...

Those aren't even my words, so if you don't agree with it, you're not disagreeing with me, but with a renowned neuroscientist. What do you think of the nerve net of a cnidarian? It's really not so different from the behaviour of bacteria and protozoa, which is similar to how the human brain...

I’m merely pointing out what my conclusions are so far, based on the information that I have. That doesn't mean that if you're right about something, I should therefore agree with you, even though I don't understand it. I never said that I'm sure that I was right about anything, or that I...

Thanks everybody for your extensive answers, especially @gleem and @jim mcnamara, this is the reason I come to this forum. You’re both providing me with theories about complex behaviour that, to me, still don’t seem to be automatically also applicable to mimicry as well. I simply don’t see the...

Well, if you argue that mimicry is not intended, it must have occurred by chance, spontaneously, randomly, and not as a strategy, right? Sure, the black and white moths example clearly shows that random mutation is the driving force of evolution, no white moth ever intended to be white, but...

Can you support your argument?

Why would any organism start investing energy into mimicking anything if it's not evolutionary adaptive? It must have been cognitively aware, already beforehand, what reward would be at the end, if it manages to do so. Organisms work backwards, from a reward at the end, back to behavioral...

Interesting article, but this is yet another example of mimicry in nature. It does not answer my question. One passage in this article in particle is quite interesting: "Many previous studies of insects such as butterflies suggested that mimicry is a stable evolutionary endpoint. Once the mimic...

Interesting! Is this your own hypothesis (which sounds very reasonable), or can you support that claim as well? If random variations did indeed gradually develop towards perfect mimicry (without even knowing you're mimicking something), then do we observe this gradual change anywhere in...

So you also think it shouldn't be called 'aggressive mimicry' then, because it's a misleading term? Yes, I've read that book, great book! I learned many things from it, like why so many parasites end up in the liver, of all the possible body organs. Many examples of many different parasites...

The green-banded broodsac, a parasitic flatworm, is said to parasitise the eye stalks of snails, and through imitating a caterpillar attracts the attention of a bird. But how does it know what a caterpillar looks like, if it doesn’t even possesses complex eyes? Flatworms have primitive eyespots...

I have done a bit of research, and found some new information to better determine the answer the the question regarding the origin of giant viruses: it involves transpovirons. Transpovirons are linear plasmids in a girus. Based on the phylogenetic analysis of the helicase domain the discoverers...

"Acute myeloid leukaemia cells were particularly rife with bacterial sequences. A third of the microbial genes came from a genus called Acinetobacter, and had been inserted into the mitochondrial genome. "Stomach cancer cells also contained lots of bacterial DNA, especially from Pseudomonas...

I can follow how they probably arose before eukaryotic cells, but I can't follow how they could have existed already before prokaryotic cells. So 'redundancy', in one way or another, must be part of the explanation here, instead of just gene capture/acquisition. I mean, a giant virus, just like...

Interesting. Could you please elaborate more?

So they must have acquired those genes then. But then the question remains: why/how would they acquire those genes?

Is it more probable that giruses (giant viruses) acquired their cellular apparatus from another cell, or that they once were a functioning cell, but degraded over time, parasitizing other cells? In the course of evolution viruses emerged many times. Viruses evolved on multiple, independent...

Because we're not a branch of the evolutionary tree like all the other animals, we're more like its trunk. Extremes die out and non extremes survive, in the sense that human health is limited by a very narrow range of dos and don'ts, and the same thing goes for the entire planet. Global...

The pessimistic future prospect. Should I stop trying to find credible and plausible optimistic scenarios?

Doesn't "probable" imply that there is an alternative? Freeman Dysan (to which the Wikipedia article is referring) here argues the following: "The prevailing view (Weinberg, 1977) holds the future of open and closed universes to be equally dismal. According to this view, we have only the choice...

I understand what you mean, but why would anyone start an argument with a false premise? Could you explain to me why the articles begins a sentence with a supposed probability, namely: "If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years...", while, if I understand...

So what this article implies is simply wrong, then? If that's your standpoint, could you elaborate? What facts/evidence support your claim?

I've read here the following: "Currently, the Moon is moving away from Earth at a rate of 4 cm (1.5 inches) per year. In 50 billion years, if the Earth and Moon are not engulfed by the Sun, they will become tidelocked into a larger, stable orbit, with each showing only one face to the other"...

On Wikipedia, it says: "Eligibility - Some nations restrict the franchise based on measured intellectual capacity". I've been searching on Google for a pretty long time now, but I can't seem to find the answer to what I'm looking for. My only simply and short question is: Which nations? To...

True, but aren't plants growing towards the light? Isn't that considered a reward for their movements? Very interesting, especially the part about "sexual frustration". "Primary food and liquid rewards serve to correct homeostatic imbalances. They are the basis for Hull's drive reduction...

@BillTre You're absolutely right, I should have provided references to my claims. Here are already some quotes from papers which support my biggest claims, let me know if you need any additional substantiation for anything I've said. I haven't read these papers from top to bottom, but I will do...

When in history did our reward system develop, in order to ensure human reproduction? And what drives lower animals to reproduce? Instinct The reward is the survival of the lineage. but do animals know this as well? Do they have some kind of consciousness that they (well, actually not them...

So, there are no quasars right now? :eek: Indeed, there were quasars billions of years ago, but none of them exist right now? Does this mean that the Milky Way looks like a quasar from the viewpoint of a quasar? I still don't fully grasp the notion that all these distant quasars (which...

Does this mean that other galaxies also see these distant quasars in all directions in the same way we do? (Because if they don't, that would imply that we're the center of the Universe, and not them). Look at this picture I've quickly drawn: if our galaxy is A, and some random galaxy is B (see...

I'm not yet able to wrap my mind around the notion that quasars are the most distant objects (the Universe’s toddler years) in all directions, as seen from the Milky Way, but at the same time this is true for a galaxy that is located somewhere in a random direction near the edge of the...

This is true for galaxies nearby, but a galaxy far away from us, say in between us and our observable Universe, isn't seeing the same distribution of quasars in all directions, right? Or is the distribution of quasars, just like the CMB anisotropy, distributed the same way for every galaxy?

Quasars are the most distant objects discovered by astronomers in the Universe. The peak epoch of quasar activity in the Universe corresponds to redshifts around 2, or approximately 10 billion years ago. An extreme redshift could imply great distance and velocity, but could also be due to...

I meant that they will remain a mystery until now, I didn't mean that they will remain a mystery in the future. But I'm sceptical whether these findings indicate that the Universe has a center (which these spherical CMB anisotropies, and spherical distribution of quasars are implying), but I...

Ah OK, so you were just hypothesizing then. I sounded a little bit like you've provided the answer to this proposed observation of which I wasn't aware, but these observations (quasar distribution + CMB anisotropies) will remain a mystery to science.