102

A tiny bit of terminology Fact In popular culture, the term fact means "something that is true". I would consider a theory as being the closest concept in science to what is called a fact in the population culture. In natural sciences, the term fact is rarely used but would have the same meaning than the one in popular culture. The reason we are not often ...


96

Short answer The concept of species is poorly defined and is often misleading. The concepts of lineage and clade / monophyletic group are much more helpful. IMO, the only usefulness of this poorly defined concept that is the "species" is to have a common vocabulary for naming lineages. Note that Homo neanderthalis is sometimes (although it is rare) called ...


74

Good observation! Gene coding for the lactase Gene LCT Mammals have a gene (called LCT C/T-13910) coding for the lactase enzyme, a protein able to digest lactose. Lactose is a disaccharide sugar found in milk. Expression of LCT In mammals, the gene LCT is normally expressed (see gene expression) only early in development, when the baby feeds on his/her ...


54

Actually, we not only consider that all human beings belong to the same species (Homo sapiens) but even that we belong to the same subspecies (Homo sapiens sapiens). So, does it really makes sense? Concept of species First, please note that the concept of species is more arbitrary than the most layman would think. I wrote my opinion about the concept of ...


50

There are two big prongs of the out of Africa theory or whichever name you wish to call it. Prong the first: fossil evidence. There are lots of different kinds of protohuman fossils. Homo erectus/ergaster are found all across Europe, Asia, and into Indonesia from about 1.5 million years or so until about 70 thousand years ago, where they stop showing up. Up ...


36

A scientific fact is something that is true. A fact cannot be proven false. This is no different from the common usage of the word. However, in science, we often do not definitively know what is true. Therefore, scientific facts tend to be observations based on specific evidence. A scientific theory is a well-supported and rigorously tested explanation of a ...


35

The problem with this question is 1) wording and 2) access. "Drink" and "digest thoroughly" are two different things. The latter does not prohibit the former. It is only lactose that is not tolerated; Calcium and other minerals, proteins, fats, etc. are also present in milk and are beneficial to the consumers if the lactose intolerance is not incapacitating....


28

Tl/dr: No, evolution is not a fact (unless your definition of fact defines evolution to be a fact, in which case it is a fact...). And if that phrase ruffles your feathers, it suggests you should read the rest of this answer. I usually wouldn't put the Tl/Dr here on this particular topic, but apparently people have been unhappy with my answer being burred ...


24

Just to point out an exception, adult cows sucking other cows' milk are not uncommon. At least, it's common enough to be a concern in dairy farms and for simple fixes to have been developed. The usual fix is just a piece of plastic pinned to the offending cow's nose that makes the suckled cow walk away. I'm not sure of how much of this behaviour is feeding ...


23

None of the answers so far have really provided much evidence, so here is a small sample of the peer-reviewed articles, based on genomic information that provides the facts that we know so far that provides us with the evidence to draw the conclusions that we do. Morris Goodman, The Genomic Record of Humankind's Evolutionary Roots, The American Journal of ...


20

Trypophobia is not a recognised specific anxiety disorder (Washington Post). It is worth mentioning that anyone can have a phobia to anything, this is merely a question of whether many people associate these spatial patterns with anxiety. Nevertheless, the response of individuals to these images can be quantified (Le et al., 2015). Ultimately the findings ...


18

The definition of species is open for debate, and this is especially the case when you try to define it from a paleontology perspective. Homo neanderthalensis was first discovered and defined in the 1860's, long before we were able to sequence their genome, which was published in 2010. There genome was different enough that most scientists would still say ...


17

It is easily observed that populations of organisms change over time, both phenotypically and genetically. With some organisms we can observe this over a few days of observation; with others we can use historical records. Therefore, evolution is an observed fact. However, most people, by "evolution", are actually thinking of "the theory of evolution ...


14

I found an interesting article in Scientific American (Coates, 2005), and I quote part of it: The condition of having no more than five fingers or toes [...] probably evolved before the evolutionary divergence of amphibians (frogs, toads, salamanders and caecilians) and amniotes (birds, mammals, and reptiles in the loosest sense of the term). This event ...


14

A likely misunderstanding of yours Now we almost don't fight with other species Misunderstanding about selection As you will go through this course, you will understand why this sentence makes little sense. A change in allele frequency via natural selection is caused by a fitness differential among genotypes within a population. The existence of a ...


13

In addition to @Remi.b's answer on the species concept, and the perils of using human definitions to try to encompass biological reality, you need to understand what "interbreeding" meant to humans and neanderthals. Fertile crosses between sapiens and neandertalis were very rare, probably less than one successful cross per generation, and there's some ...


12

In a genome that is 3 billion base pairs, a difference of 0.5% works out to a difference of 15 million bases. When a single base change can change the amino acid sequence of a protein, that can add up to a huge amount of diversity, which is what we see over the nearly 8 billion humans on the planet, and the 99.5% sameness is why we are linked together so ...


12

As someone who is very disgusted by this kind of image, I think it is a caused by an association with maladies like burns, infections, and especially parasites. It is difficult for me to even describe this without feeling a bit nauseated, but it is hard for me to see things like that without picturing it being my, or someone else's, skin. Or that it is ...


12

Here is a bit of a tangential example, because it isn't milk from cows. There are some varieties of ants (Primarily the Leaf-cutter ant, if memory serves) which will collect, breed, feed, protect and "milk" aphids for the honeydew they produce. It is generally classified as a mutually beneficial symbiotic relationship, though one could argue that it is ...


11

Issue in your introduction I thought that massive changes among organisms are over long periods of time. Actually, some evolutionary events can happen on a very short time scale. A single mutation can have a massive impact on the phenotype of an individual (see for example Doebley 2004). If this new phenotype has much higher fitness, then the mutation ...


11

Just 6 million years ago, a single female ape had two daughters. One became the ancestor of all chimpanzees, the other is our own grandmother. Short answer Whether or not the claim is true actually depends upon the specific DNA sequence you are considering. The claim is true for sequences without recombination (such as mtDNA and most of the Y chromosome). ...


10

With about 20 square feet of skin constantly exposed to potential irritation, itching must serve an important protective/defensive function. The "scratch reflex" (I'm not sure I would call it that) is necessary to life and limb. Itch is a major somatic sensation, along with (and different from) pain, temperature, and touch. Itch can be an acute sensation, ...


9

I am not very happy with most of the answers here as they seem to be too ideologically motivated and not so much about scientific reasoning. So I decided to give it another try. Is Evolution really a fact and not just a theory? If this is too long for you, let me just say this: Evolution is an existing phenomenon. There is variation, there is selection ...


9

Pigs can. At least one milk, and milk derivates, producer around here used/uses their own pig farms to dispose of all byproducts of production, overdue products returned from stores, same day unused milk, etc. As they owned the pigs, that should not cause too many problems. I also remember a photo of depression era USA where a farmer is giving milk to pigs. ...


9

The Yohn et. al. (2005) paper (from Evan Eichler's lab) is describing a single type of endogenous retroviral element (loosely think of it as a 'species'), called PTERV1. They show that there were multiple independent infection events that resulted in permanent integrations in the ancestors of modern species (~3-4 MYA in the ancestors of gorillas and chimps, ~...


8

Welcome to Biology.SE. About your post It is a very standard question and a common source of misunderstanding from the general public. If you just google do we descend from monkeys you will get tons of hits that will answer your question. Because this question is introductory and has already received a lot of answers online, there is therefore no point ...


8

Every species on the planet is "transitional" - this is because there is no ultimate or final species. Species branch out from one another, sometimes species go extinct, leaving gaps between the extant branches. But it also comes down to how you look at it; if you were comparing blue whales and humans, then chimpanzees (and many other species) would be "...


8

The post is way too broad. Many questions are unclear and many questions lack research from your part. But I still wanted to give you some info that may help you. Answers will be short but it would take a whole book to fully answer all questions. You are often using "They" to refer to some undefined group of people and give a random straw man. Please always ...


8

It didn't, the basal condition for humans is dark skin, all other pigmentation patterns evolved from it. Additionally Dark skin is not monophyletic/homologous in humans, that is some darks skinned humans evolved from light skinned humans who in turn evolved from ancestral dark skinned humans, (Evolution made skin lighter then made it darker again in other ...


8

Because we as humans are really really good at picking up small differences in humans and really really bad at detecting them in anything else. Animals are often quite good at telling each other apart, far better than humans are, birds in particular are known for this. Just because you as a human are bad at it does not mean they are. There is a pretty ...


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