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Questions tagged [evolution]

Changes in the heritable attributes of populations of organisms over time. The mechanisms of evolution are mutation, migration, drift, and selection.

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Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?

It is an often-repeated claim that human, and in fact all animal blood is salty because we evolved from aquatic organisms, and that blood has a similar concentration of salts as ocean water, or at ...
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What is the difference between atavism and retrogressive evolution?

It seems like both concepts talk about the re-appearance of primitive characters, and I'm quite confused about the difference between them. Any help is appreciated.
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What is the relationship between r/K strategy and filial infanticides?

In other words, is the frequency of killing one's own offspring among species dependent on their location on the r/K strategy spectrum?
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good genes hypothesis and handicap principle (definition)

I see "good genes hypothesis" and "handicap principle" are often defined in the same manner (e.g., here or here), but I can see they are probably not the same thing. While I can find much information ...
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1answer
69 views

Are any genes over a billion years old?

Are there any genes (for any organism) for which we can say with confidence that they are over a billion years old?
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How would have RUBISCO evolved if photorespiration had occurred in early life?

It is said that when RUBISCO evolved, the atmosphere was high in carbon dioxide with very little oxygen. Because of this, photorespiration never occurred and there was no selection pressure against it....
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Why is synthesis of tetanospasmin advantageous to C. tetani?

The tetanospasmin is a neurotoxin synthesised by some strains of C. tetani. It is the factor causing tetanus, but what is its role for the bacteria itself? I do not believe the main objective of C. ...
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39 views

How can molecular clocks be 'calibrated'?

I want to know, in general terms, how molecular clocks can be ‘calibrated', taking into account the possible approaches for estimating it over 10s or 1000s of years (or longer geological time periods)....
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1answer
34 views

Mechanism to limit the exponential growth of the number of ancestors that are n-generations away from an organism?

The context is organisms with sexual reproduction, with 2 parents per organism. Construct the family tree of one such organism, back into geologic time. Take a(n) as being the number of ancestors ...
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1answer
92 views

Are all of my ancestors from 400 million years ago fish?

Say you have your family tree for the last 400 million years or so, back to the Devonian, the age of fishes. You take the set of ancestors that are about 400 million years old (which will be across ...
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0answers
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Could the octopus be evidence of the evolutionary inevitability of intelligence? [on hold]

There is a claim that because the octopus is so different from other life forms on Earth and is so intelligent (supposedly appearing relatively rapidly) that it must have an alien origin. While the ...
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0answers
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Characteristics of a giant squid’s skin

Is the skin of a giant squid/colossal squid similar to the common squid? Does it possess chromatophores to change color? Or did it lose that ability because of the depth at which it resides or due to ...
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1answer
51 views

What is the evolutionary advantage of the Mane?

Horses, Donkeys, Antilopes and Bovines seem to have an evolutionary advantage in growing masses of hair on top (and sometimes below) the neck. Is that to hinder predators biting?
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1answer
66 views

Why is facial symmetry of the opposite sex attractive?

Why do we give so much importance to the symmetry of face in the opposite sex? Why do we yearn to reproduce with a person with a beautiful face? How is it important for survival, if at all? Is there a ...
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0answers
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Why can't geese regurgitate food?

I saw this harrowing video on how barnacle goslings have to jump off very high cliffs because the parent's can't feed them. The death rate seems high. Why did natural selection come to favor jumping ...
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Why do komodo dragons have covered teeth?

Apparently komodo dragons have a layer of gum over their teeth and often bleed from the mouths because of this layer being lacerated when they bite. Does this layer of gum serve any evolutionary ...
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2answers
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Why have ground beetles never evolved the ability to get back up?

This may seem like a funny question, but I've seen so many ground beetles upside down on the floor and wondered why they've never evolved the ability to get back up. Wouldn't something like this ...
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0answers
66 views

How does antagnostic coevolution work in ducks?

I recently learned that in ducks, the penis and vagina have coevolved: the vagina of the female ducks gets dead-end sacs and clockwise coils; the penis of male ducks become longest and its morphology ...
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Inheritance percentiles

I am aware that the average DNA contribution from each grandparent is 25%, while the possible range is 0%-50%. I found a source citing 18%-32% as the "normal" range but this was undefined. I assume ...
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Does intelligence depend more on environment than on genetic factors? [duplicate]

Many have argued that the test of IQ is simply a test of language. The application of the test consists of asking a number of questions. The person should understand the question presented to them and ...
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1answer
34 views

What causes the elongation of Genome down the evolutionary time line [closed]

Theory of natural evolution says that complex life forms arose from simpler ones e.g. starting from Eubacteria to modern day multicellular eukaryotes. {If we try to reduce these changes happening at ...
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4answers
107 views

Is variation a result of Evolution?

We know that the DNA copying mechanism that replicates DNA during cellular division is not 100% accurate and the resultant errors are the source of variation in the members of a population. At the ...
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0answers
14 views

Is recapitulation theory correct? [duplicate]

Most school books still say that recapitulation is an evidence of evolution but as far as I know it has been proved wrong so why is it being still taught? Has it got any sort of relevance?
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1answer
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Were there any vertebrates with 6 or more limbs?

My question is actually a bit more broad than what's in the title, but I don't know how to put it succinctly. When I was trying to find the answer to that question, I found that all known terrestrial ...
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Sharks, alligators and Gould's “random walk” theory

I was thinking about Stephen Jay Gould's view on evolution as pure "random walk" / Drunkard's Walk, increasing or decreasing complexity in basically random fashion, just limited by death if an ...
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0answers
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Who invented dN/dS?

I am writing a paper, and I want to refer to the original paper that coined the term dN/dS (or Ka/Ks for that matter). I have found early works on dN and dS (like Miyata and Yasunaga 1980), but cannot ...
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Comparative evolutionary study: is amino acid or nucleotide comparison more useful?

I am a high school student and am currently learning about evolutionary relationship study in biology. My teacher said that a comparative study of amino acid sequences is more useful than a ...
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0answers
32 views

Are there any evolutionary reasons for the different tree shapes? If so, What are they?

So we know there are a thousand types of trees with different shapes. We have Columnar shaped trees: Pyramidal or Conical shaped trees: Weeping shaped trees: And we also have Round, Vased, Open-...
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35 views

What are the methods for detecting anagenetic versus cladogenetic change?

I'm new to the study of phylogenetics and am wondering if there are ways of identifying evolutionary changes that associate with cladogenetic events versus those that arise via anagenesis.
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1answer
47 views

What is the biological advantage of bilaterity?

I was wondering why there were so many bilateral species (under the bilateria clade) in comparison with the cnidaria clade. I have two or so questions: Am I (or are we) unaware of the diversity and ...
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1answer
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Are there examples of animals being sexually attracted to another species more than to their own?

I just thought that from the perspective of a female domestic cat, a male bobcat probably looks like the archetype of a perfect mate. As tall, strong, muscular and mighty as it possibly gets. Clearly ...
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56 views

Laurasia and Gondwana [closed]

The Cambrian explosion was 540 mya. Laurasia and Gondwana didnt collide until 330 mya. So for 210 million years the land was divided into two large continents. Plants and insects had already colonized ...
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1answer
34 views

Is there a system biology approach to compare pathways or famillies of proteins from an evolutionary point of view for the same organism?

I would be interested to know if there is a method/analysis or a set of methods to compare two groups of pathways or families of proteins. I would specifically be interested by a system biology ...
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2answers
59 views

regarding evolution of ears and sense organs [closed]

How could we(or any other organism) have developed ears through evolution when before having ears we did not know that sound waves existed or there was anything such as hearing? How did the first ...
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1answer
48 views

Probability for a megafauna specimen to exhibit a gene not present in either parent

What is the rough probability for a megafauna specimen to exhibit a gene not present in either parent? I'm looking, ideally, at the chance for one specific individual to be the first in a breeding ...
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1answer
55 views

Estimate for number of genes changed in speciation between a megafauna parent and child species [closed]

At least in terms of a back-of-the-envelope calculation, what is a believable range for the number of gene changes between parent and child species to represent speciation between species of megafauna?...
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1answer
36 views

Did the first cell self-replicate or was it multiple first cells? [closed]

We're almost sure by now that the first cell was born in a some kind of underwater vents environment which harvested all the necessary conditions for it to exist. However, did the first cell self-...
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1answer
48 views

Why do death cap mushrooms not warn of their poison?

This has been puzzling me for a long time now. There is an evolutionary predilection for living things which have evolved strong defensive measures (that may not themselves be visible) to give ...
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1answer
64 views

What's the evolutionary purpose of having hearts?

According to this New understanding of heart evolution Humans, like other warm-blooded animals, expend a lot of energy and need a lot of oxygen. Our four-chambered hearts make this possible. It ...
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0answers
19 views

Phylogenical differences with nuclear and mitochondrial DNA

This is a textbook question, I would like to verify my answers. According to the textbook it is possible to construct a phylogeny using nuclear and mitochondrial DNA and these trees to be different, I ...
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0answers
34 views

Why are ducks more cautious than pigeons? City park paradux

In my city park there are mostly two types of bird: -Mallard duck -Rock dove (pigeons) When I feed pigeons, they approach me very close. Sometimes they peck the food that fell on my feet. If I hold ...
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1answer
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creating life in the laboratory [closed]

Originally life came about through non life but Scientists are unable to achieve this in a laboratory . Why is this ? Is it the time factor ? I believe that it took one billion years for life to ...
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1answer
56 views

Is bacillus strain 2-9-3 really 250 million year old?

I've read that in the last decade (I believe) some scientists discovered a microorganism, which they dubbed bacillus strain 2-9-3, in a crystal of salt that they think is 250 million years old and ...
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1answer
184 views

How hard would it be to create a protein “by chance”?

I just read an article about David Gelernter, who was arguing against Darwin's theory of Natural Selection. He said one particular thing which stood out to me: "...how hard it would be to create just ...
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Species specific White Blood Cells (WBC) composition

In our ongoing immunology undergrad course I learnt that neutrophil primarily fights off bacterial infection and lymphocyte is produced in response to viral infection. I also learnt that neutrophil ...
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1answer
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Why have plants evolved to photosynthesize glucose instead of another molecular compound?

I think this question can be broken down into two sub-questions: Why do plants produce $C_6H_{12}O_6$ as opposed to another molecule following the formula of $C_nH_{2n}O_n$? Why not $C_8H_{16}O_8$, $...
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1answer
75 views

When is it reasonable to assume selection for an observed change?

In speciation events, a lot of changes seems to appear simultaneously. How can a specific partial changes, occuring together with a lot of other changes, be said to be advantageous or disadvantageous? ...
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2answers
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Why isn't the human zygote considered a human life how is a living anatomically modern human defined biologically? [closed]

It has 46 chromosomes by default when healthy(Differences almost always are pathological) and has almost every biological functions, processes a Newborn or and Adult person has. It even invades ...
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1answer
91 views

What is the function of spongin in sea sponges?

Sea sponges (Porifera) use different types of skeletons to support their structures. Some skeletons are built from minerals, some are built from proteins like spongin, and some use both. My question ...
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0answers
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Evolution in Biology Species [duplicate]

what a species is, why it is so difficult to define, and how we should best determine the boundaries between species. This is the basic general definition: A species is often defined as the largest ...