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Limiting the conversation to mammals, and taking relative brain size as a proxy for intelligence (which, of course is not necessarily "true", but at least is quantifiable), the answer is yes: body-size relative brain size correlates with body-size relative longevity in mammals. using a global database of 493 species, we provide evidence showing that ...


10

I think we may be missing a piece from Darwin's original hypothesis. An outline of the first 4 chapters of Origin of Species form the kernel of the Theory of Evolution: 1: Variation under Domestication 2: Variation under Nature 3: Struggle for Existence 4: Natural Selection Really you can't reduce evolution to less than variations; competition (struggle)...


10

Addressing some assumptions/presumptions apparently present in the question (this might be too long for a comment): First, natural selection has not stopped. The sexual selection might be more active than ever, so there is ongoing "pro-fertility" selection and some segregation "pro-smarts". Not every member of contemporary potplation is capable, even with ...


8

A few words on genomic prediction No complex trait is 100% heritable, hence no prediction based entirely on DNA would ever be perfect. With that said, predictive genomics is progressing at a quite amazing rate right now. So while predictions can be nowhere near perfect, it is getting possible to make DNA predictions that correlate substantially with ...


7

Several issues here that make your question unanswerable: Intelligence is not defined. How would you define it? What kind of relationship are you exactly looking for? Comparing average intelligence between groups or trying to fit a regression with intelligence on the Y-axis and relatedness to human on the X-axis? The general issue hidden behind methods of ...


7

You are right. Inbreeding strongly increases overall homozygosity which subjects inbred individuals to diseases caused by rare recessive alleles. In non-inbred individuals the chance is quite low to receive those because many deleterious variants (and in fact, most segregating alleles we can observe) are recessive. Most often, but depending on the dominance ...


6

There are an estimated 100 billion neurons within the human brain. In general a minor variation in the number of neurons should not effect individuals too much, however when there is a more significant loss, such as brain injury or in some forms of dementia cognitive abilities do decline. So in this sense yes the number of neurons does relate to intelligence....


6

I don't really know what you mean by "abandoned children". Adopted children? Children in the wild? Have you read the Wikipedia article on the subject? If you want to know how it was studied, just take a look at the references, it's pretty straightforward. Heritability simply means how much variation in a trait is due to genetics, which is usually ...


6

You seem to think that living in the natural environment is "easy". But, even when the climate helps, even when you have no war to fight or defend against, even so you have to know the habits of the animals which you will hunt, the fishes you fish, the proper season of the plants (fruits, fibers, roots...), which of them could be toxic, which could be ...


5

Intelligence is something which has to have a definition, and there are many, but I would cautiously say no. The reason that I say this is because swarming behavior can be largely reproduced by a simple set of rules - matching distance to your neighbors and direction and speed as well. To me this really removes any intention or even conscious element to ...


5

Evolution is largely random, because most of the processes that drive evolution are random. A few ideas you should understand to realize why it is so random. Most people are only aware of natural selection when it comes to evolution, and think that natural selection has a goal of creating new, increasingly sophisticated forms of life. None of this, of ...


5

Too long for a comment: Evolution and mutation has nothing to do with intelligence and is not influenced by the cells itself. It happens by chance and if the mutation turns out to be beneficial (or at least not harmful for the moment) it will be a selection advantage. Something to think about: If a mutation in an enzyme which is responsible for Glucose ...


5

I know of no correlation between number of neurons in cortex and intelligence. This question is fraught with controversy because there has been very little work on it but much speculation. Some have suggested that the connectivity between neurons is what is important rather than the number which is logically possible but remains to be supported by definitive ...


5

I think the question mainly highlight either of two misunderstandings: misunderstanding about the definition of heritability misunderstanding why the slope of the regression line is equal to heritability (in the narrow sense). Definition of heritability Please have a look at the post Why is a heritability coefficient not an index of “how genetic” ...


5

When talking about increasing intelligence there are a few things you have to keep in mind. Can you increase your IQ score? Probably, yes. Just take the same test twice, or more realistically practice a lot of IQ-type problems. You will probably raise a few points. But this is just a score. When experts are talking about raising intelligence, they are ...


4

Unlike a computer, the speed at which any brain can perform a computation is related to the number of synapses it goes through. This means fewer synapses in series correlate with decreased reaction time. An example of fewer neurons correlating with a decrease in reaction time is exemplified in sensory neurons. All sensory nerve cell bodies are all located ...


4

It might not fully answer your question… Cost of having a heavy brain Generally speaking, having a heavy organ is an important cost for flying animals, a medium cost for terrestrial animals and a low cost for marine animals. Loosely speaking, the principle "use it or lose it" does not apply with the same strength in all animals in regards to brain weight. ...


4

As a Drosophila biologist, I will attempt to address the above question by giving an examples from the Drosophila field. When this paper (http://www.ncbi.nlm.nih.gov/pubmed/7720066) in Cell came out, it sent shockwaves around the world since it showed a molecular mechanism by which production of cAMP and activation PKA, effects CREB transcriptional ...


4

Indeed, C. elegans nematodes (which are the ones you are talking about) do not show cognitive responses. AFAIK, Drosophila melanogaster is also able to learn and display some quite complex behaviors, but no cognitive functions. I believe the "simplest" organism known to display what could be called "cognitive" functions is the honeybee (see for example this ...


4

Problems of epistemology in your question Two problems of epistemology (which discussion is a matter of philosophy rather than science) The whole question depends on what you consider being random and what you consider being determinist. The number that come out from a dice is random unless you know exactly how the dice was thrown (and make some ...


4

IQ is just a measure of how good you are at taking IQ tests, that's it. Those tests are usually culturally biased towards middle income first world citizens (among other things). Think of it this way, questions about mortgages, supermarkets, airplanes, or such thing presuppose the person being questions knows a reasonable amount about those things, this is ...


3

I believe its the other way around - humans may engage in riskier and more novel behavior when infected... which is the most interesting part of the story. Its not cut and dried, but I think its quite possible that risky behavior increases. T. gondii is a parasite whose typical life cycle includes both mice and cats as hosts. The transmission involves ...


3

A classic study of IQ heritability is Skodak & Skeels (1949). They studied heritability of IQ in children who were adopted at a very young age, with IQ data of the children, of their biological mothers, and of their adoptive mothers. It is important to keep in mind that heritability is a measure of the proportion of variance that is attributable to ...


3

Nature isn't intelligent, genes aren't intelligent, and evolution doesn't have a purpose or a goal. Mutations are random, and roughly 97% of them are deleterious while roughly 0.03% are advantageous for the species. This is the first prerequisite of evolution. The second one is differential survival. An organism with a better chance to survive or reproduce ...


3

There appears to be some - note that this, of course, is highly controversial - evidence pointing at the direction that intelligence declined in the US and UK during the last century. There is a relatively new review by Michael Lynch (2016) in which he suggests that modern humans are accumulating slightly deleterious mutations with increasing rate due to ...


3

I think this website provides a pretty surprisingly thorough breakdown of avian brain anatomy, including historical contexts and debate around what exactly is homologous and what is not, and whether 'homologous' is a useful bit of information. In short: It was thought until recently that the bird brain was just the core of the mammal brain with some layers ...


3

Yes, there is a lot of evidence for self-awareness in animals. The gold standard test for self-awareness is the mirror self-recognition test (MSR)--we can tell from the behavior of an animal exposed to a mirror whether or not it can tell itself apart from other animals of the same species: Animals that possess MSR typically progress through four stages of ...


3

To answer your question, we must first ask the question What is defined as intelligence? A googling will tell you that most people believe intelligence to be something related to apes or even more conservatively to humans. But, I find this to be a bit unpragmatic. The closest level of abstraction I find towards defining intelligence is this wiki on Animal ...


3

I don't think this is really a biology question; philosophy, maybe. Or for the history and philosophy of science. The main problem is: what does "INTELLECTUALLY equivalent to" actually mean? What sort of equivalence is it? There isn't a convenient Mohs scale we can use to measure the hardness of problems. We don't actually have a good biological model of ...


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