Tagged Questions

Changes in the heritable attributes of populations of organisms over time. Major mechanisms include drift, natural selection, mutation, and gene flow (migration).

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How did giraffes develop their rete mirabile failsafe?

Giraffes, being one of the tallest mammals in the world, have a failsafe called rete mirabile to prevent them from dying from excessive blood pressure while lowering their head.[1] Due to their long ...
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1answer
300 views

Fossils of intermediate stages?

If Humans are evolve from Monkeys, there must be stages in the evolution process, when it was 1% human and 99% monkey, 2% human and 98% monkey and so on. This is because evolution was a very slow ...
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Birds from the Family Columbidae Feed Young “Crop Milk”

Birds from the family Columbidae (e.g., doves and pigeons) produce a fatty, milk-like substance in their crop. The secretion is often referred to as "crop milk." They feed crop milk to their young ...
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138 views

What selective factors drove the evolution of lactose in lactation?

As far as I can determine, lactose, and the monosaccharide galactose have few biological uses outside of mammalian lactation. It not only required enzymes for its production, but enzymes in offspring ...
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Does pheomelanin have a useful biological function?

Melanin is a natural pigment that is categorized into two main forms, eumelanin and pheomelanin. It's well documented in the science literature that increased eumelanin levels reduces the risk of ...
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135 views

Is better healthcare a bane to the long-term survival of the human race?

The theory of natural selection has it that individuals with better genes tend to survive and reproduce, passing their genes to their offspring. This gradual process results in a population more ...
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Is there any evidence that a virus can modify human evolution

I was just reading Evolution of lactose tolerance, and in it one line says "But there was a time in human history when our diet and environment conspired to create conditions that mimicked those of a ...
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5answers
715 views

How is evolution possible in contemporary humans?

I would like to know if evolution is continuing to happen in modern humans, assuming things like existence of the nuclear family structure, fidelity to one partner, etc. It seems to me the answer ...
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1answer
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What evolutionary pressures pushed Galápagos tortoises to mature so slowly and live so long?

I read that they take up to 40 years (in the wild) to reach the age of reproduction and are thought to live over 100 years, with one in captivity reaching over 170 years. Can someone explain in ...
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2answers
235 views

Were there lifeforms before LUCA?

This question got me thinking about something. LUCA is the last universal common ancestor of all current living organisms, which is a very different definition from the first-ever living organism. Is ...
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3answers
260 views

Are there genes in humans from the common ancestor of all organisms?

How long ago can human genes be traced? Are there any genes that go back unchanged to the beginning of life on Earth? And if so, how many?
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What is the difference between orthologs, paralogs and homologs?

These three terms are often misused in the literature. Many researchers seem to treat them as synonyms. So, what is the definition of each of these terms and how do they differ from one another?
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Has the human 7-day week had any impact on the evolution of species?

Most (if not all) industrialized countries follow a 7-day work week now, such that we are bound to follow a certain weekly trend in matters such as pollution generation, where to go (e.g. stay in town ...
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Why can't humans drink sea water?

Why can't humans drink sea water? It would seem to be a huge evolutionary advantage for an animal to be able to drink sea water rather than have to rely on fresh water, and it's provably not ...
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1answer
146 views

Can epigenetic changes affect reproductive success?

This is prompted by niallhaslam's answer to this question [Since Darwinian times, has there been any striking/notable effects of evolution on humans?]. A comment by Alan Boyd asks whether epigenetic ...
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1answer
54 views

Biology view on trait variability

In reading the annotated Origin... I have come to the following note by Costa on p. 168: Again, modern biologists would disagree with Darwin's idea that especially well-developed traits vary to a ...
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148 views

Since Darwinian times, has there been any striking/notable effects of evolution on humans?

I understand that evolution is constant process that acts on a population in successive generations. Thus, it is obvious that evolution is happening. However, I'm curious as to the stricking examples ...
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Is there an evolutionary reason for the 5 electron transport complexes in plants and animals?

The electron transport chains of both the light reactions of photosynthesis (in plants) and oxidative phosphorylation (in animals) both contain 5 complexes including ATP synthase, as shown below. ...
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1answer
51 views

Preserved alpha complementation over evolutionary time?

Has the result of alpha-complementation ever happened via mutation through evolutionary time, and been preserved in modern day organisms? In other words, has a functional gene product ever been split ...
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1answer
164 views

Is it possible to increase lifespan through controlled evolution?

A few years back when I was reading The Selfish Gene by Richard Dawkins, there's this short passage where he theorizes about a way to achieve an increased lifespan through controlled evolution. The ...
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1answer
141 views

Why was polyploidy not lethal in certain octodontid rodents?

As discussed in Why is polyploidy lethal for some organisms while for others is not?, polyploidy is normally lethal in mammals. However, two species of Octodontidae (South American rodents), are ...
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362 views

Why did mammals evolve to have two testes?

What makes mammals tend to evolve to have two testes?
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2answers
93 views

Have proteins been observed to come into existence through mutations and natural selection?

What is an example of a functional protein that has been observed (in real time) to have come into existence through mutations and natural selection (not through an existing one being made defective). ...
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Why are some berries poisonous?

In my understanding, the evolutional function of berries is to be eaten and pood out somewhere else, so that the seeds of the plant spread. Is this so? Then why are some berries poisonous?
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How exactly are game theoretical evolutionary models described during implementation for computer simulations?

When a biologist or a layman tries to reason the evolutionary explanation for something, they would simply use English with some math thrown in (for a random example, pick any explanation out of "The ...
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Is there an advantage to linear chromosomes?

The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
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1answer
219 views

From which ancestor species did humans inherit orgasm?

From what ancestors did humans inherit orgasm? Do fish experience orgasm? Are the male and female orgasm the homologues that can be traced to the time when there was no difference in sex between ...
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Is vision a vestigial sense for deep ocean species?

Sunlight doesn't penetrate beyond a couple of hundred feet from the surface of the ocean. Species that exist at greater depth probably live in a state of perpetual night; yet from a quick google image ...
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Evolutionarily speaking, why do humans have 46 chromosomes

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Monkeys, chimpanzees, and Apes have 24 pairs (twenty-four pairs), for a total of 48. What caused humans to have 46? ...
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Human evolution: Where *exactly* did the first human come from, whose parents were not?

Layman here. So I have never really quite understood this facet of human evolution, (or any other for that matter), in that, I understand the evolutionary process, but I get lost on the 'border' ...
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3answers
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How did butterflies evolve to have eyes on their wings?

Some butterflies, such as the UK native Peacock butterfly (Google Image Search) have markings on their wings that look just like eyes, complete with a white fleck to imitate a convex, transparency ...
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1answer
92 views

Predators faking to be not hungry?

I believe that there are predator/prey combinations where the prey can easily spot that the predator is not hungry and will not try to flee from it. I’m thinking, for example, of gazelles who will ...
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1answer
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Disadvantages of unihemispheric sleep

Is is well known fact that marine mammals and some birds can sleep with one brain hemisphere at a time, since it's essential for their survival. However, at least in my opinion, such mechanism would ...
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2answers
162 views

What is the Edward O. Wilson fuss about?

I have just read this article on E. O. Wilson and I don't understand what the difference is between what he is arguing and "standard" natural selection. I read "the extended phenotype" some years ago ...
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Why don't flies avoid the motorway?

Flies have a short lifespan, therefore evolution should technically happen over a shorter period of time (years). Flies die all the time from getting hit by cars on the motorway. Those flies that ...
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5answers
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Why did life not evolve to use radio?

We use electromagnetic communication everywhere these days. Cell phones, wifi, old-school radio transmissions, television, deep space communication, etc. I'm curious about some of the possible ...
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1answer
254 views

Evolution of long necks in giraffes

In this question, the OP uses giraffe necks as a supportive example of evolution. Is the mechanism described in this post accurate? At some point, I thought I remember hearing that giraffes did not ...
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3answers
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Is the theory of evolution being disproved by bats?

For some species the Darwin's theory evolution makes perfect sense. I can easily imagine how, for example, the giraffe has evolved to its current appearance: the natural selection was favoring ...
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1answer
367 views

Can parents' learned traits be transmitted genetically?

I am wondering whether a behavioral trait (e.g. fear or stress experienced in the lifetime of the parent) can be transmitted genetically to its offspring? I understand that a behavioral tendency for ...
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869 views

Why don't all ants have wings?

Since the new queens-to-be have wings, it means that ants either evolved from insects that can fly, or insects that can fly evolved from ants, or that we have a case of parallel evolution (which is ...
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1answer
283 views

Computational/mathematical models for predicting phenotype from genotype

Karr, Sanghvi, et al. (2012) propose a whole-cell computational model for predicting phenotype from genotype in Mycoplasma genitalium. Their model simulates myriad cell processes such as DNA ...
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226 views

Short-term Lamarckism in asexual single cell organisms

I was reading through the Karr et al. (2012) whole-cell computational model. One of the things they did was to induce single-gene disruptions in their model. They observed several to be fatal, but: ...
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901 views

How does evolution produce complex organs

I've been wondering lately how evolution manages to produce complex organs. It is pretty obvious to me how evolution would select some minor traits like size, resistnce to illness or climate. There is ...
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1answer
412 views

How and when did a dedicated immune system evolve?

I have recently been doing a lot of research into the interplay between the innate and adaptive immune systems in humans, and mammalian laboratory models. This has led to my reading some interesting ...
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Why is glucose our primary source of energy?

Is there any evolutionary reason for glucose being the "main" molecule used as a source of energy, beginning with glycolysis and subsequently cellular respiration (after being converted to two ...
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415 views

Introductory books about evolution

This days I read some debates on evolution. That made me more interested to read something reliable on topic - I mean books. I'm christian - although I think it doesn't matter on that topic - and I ...
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170 views

Is there an “evolutionary species similarity calculator”?

Is there a website where I can input pairs of species and get an "evolutionary similarity score"? E.g. (numbers are completely made up) Input: Chimp and Human, Output: 97% Input: Cat and Human, ...
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1answer
183 views

Why would deers keep crossing a river full of crocodiles while some of them have been killed?

I recently watched a clip on Discovery Channel, where I saw deers crossing a river full of crocodiles, ignoring the fact that some of them would have been killed doing so. What could be an ...
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4answers
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Why are there exactly four nucleobases in DNA?

Does someone know why DNA is composed of four nucleobases? In particular, is there an explanation for the number? Why four and not two, or eight?
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How did the first self replicating organism come into existence?

When people try to explain evolution, they tell me that evolution is a cumulative result of mutations & natural section of the more superior individuals of a particular species. I think I'm fairly ...