Probabilities of the gene appearing that made humans smart?

[Apple_Mango]

What exactly was the probability of the genes manifesting that give rise to human intelligence?

The event must be incredibly rare seeing how there were several species of animals yet humans are the only one who can do complex math and language.

 

[NFuller]

What exactly was the probability of the genes manifesting that give rise to human intelligence?

I am almost completely sure there is no known answer to that. There are probably many ways to build a highly intelligent organism. We are just one example, but we are the only example known. Thus, it is difficult to give a generalized answer to such a question.

The other issue is how far back do you want to go? If we start with primates and ask what mutations are necessary to get to a human. The answer is not too many, and if environmental conditions are appropriate, you can get a human in just a few million years. If you want to start from the first cell, then the probability to get to human is likely very small, but the probability of developing an intelligent organism may not be, given enough time.

The event must be incredibly rare seeing how there were several species of animals yet humans are the only one who can do complex math and language.

Remember that we are not the only species of human that existed; there were several others too. Those others also had abilities to make specialized tools and have complex social interactions.

 

[Apple_Mango]

Is it even possible to find out the answer to my question?

 

[NFuller]

Is it even possible to find out the answer to my question?

I think your question is too general as stated. If you can be more specific, like asking about particular named mutations, then you may be able to find an answer.

 

[Drakkith]

Is it even possible to find out the answer to my question?

Unlikely. I don't think we even know all of the exact mutations that make us so much smarter than other animals. I believe we know a few, but I don't think we know all of them since our intelligence is probably the result of many different genes working together in ways that are complex and difficult to figure out.

 

[Ygggdrasil]

There are two issues here:
1. We don't really understand which genes are responsible for human intelligence. Likely, the answer involve many different genes working together and some of the evolution has not been in changing the genes themselves, but the non-coding DNA sequences that regulate their expression.

2. In general, evolutionary biologists debate the extent to which evolution is reproducible and predictable. Stephen J Gould proposed the thought experiment considering what the Earth would look like if we were to rewind time a few hundred million years to an identical starting state and let evolution proceed to present day. He thought it would be likely that we would end up with a very different set of species populating the Earth were we to "replay the tape of life" in this way. Indeed, evolution has been shaped by many chance events (e.g. a mass extinction caused by a meteorite strike). Furthermore, many of the underlying processes of evolution, such as the appearance and propagation of new mutations in a population, are stochastic and rely on chance.

In recent years, there have been efforts to simulate evolution in the library to address questions about the predictability and reproducibility of evolution. For example, Richard Lenski seeded 12 identical populations of E. coli in the 1980s and has been tracking their evolution for the past three decades, providing insights into how new traits evolve in bacteria (e.g. see http://www.pnas.org/content/105/23/7899). Researchers are also combining computational and experimental approaches to look at the evolution of proteins and understand the reproducibility of evolution at the molecular level (e.g. see this recent paper from Joe Thornton's lab at the University of Chicago: http://www.nature.com/nature/journal/v549/n7672/abs/nature23902.html). For a general review of the reproducibility and predictability of evolution, see this review article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4633862/

Of course, these experimental approaches are on simple systems (fast-reproducing bacteria) and simple traits (often encoded by a single gene). Studying a complex trait like intelligence in a slowly reproducing organism like humans would be very difficult.

 

[Drakkith]

1. We don't really understand which genes are responsible for human intelligence. Likely, the answer involve many different genes working together and some of the evolution has not been in changing the genes themselves, but the non-coding DNA sequences that regulate their expression.

Indeed. That reminds me of the following parody song, which explains this very fact:

Who knew you could learn so much from a parody song? Also, I want to give whoever named the Sonic Hedgehog gene a round of applause. That used to be one of my favorite video game franchises.

Ygggdrasil, do you happen to have any good links about what we know makes our brain growth different from that of other apes?

In recent years, there have been efforts to simulate evolution in the library to address questions about the predictability and reproducibility of evolution. For example, Richard Lenski seeded 12 identical populations of E. coli in the 1980s and has been tracking their evolution for the past three decades, providing insights into how new traits evolve in bacteria (e.g. see http://www.pnas.org/content/105/23/7899).

What an amazing experiment. I was astonished when I first read about it.

 

[Ygggdrasil]

Ygggdrasil, do you happen to have any good links about what we know makes our brain growth different from that of other apes?

Unfortunately, my knowledge of biology drops precipitously when discussing things larger than cells and I am not very knowledgeable about neuroscience.

 

[rootone]

What exactly was the probability of the genes manifesting that give rise to human intelligence?

What is the probability that you get a big win in a lottery?
It's greater than zero.

 

[cosmik debris]

What is the probability that you get a big win in a lottery?
It's greater than zero.

Only if you buy a ticket.

Cheers

 

[Ygggdrasil]

Related somewhat to another thread on interbreeding between ancient hominid populations, I read an interesting article about researchers studying DNA sequences in modern day humans that originated from Neanderthals. In particular, the researchers have been trying to study areas that are less likely than average to contain Neanderthal sequences:

Geneticists at the meeting also zeroed in on archaic DNA “deserts,” where living humans have inherited no DNA from Neandertals or other archaic humans. One of these regions includes the site of the FOXP2 “language” gene. The absence of archaic DNA suggests that in our ancestors, natural selection flushed out the Neandertal version of this gene.

Using software that evaluates gene expression, Vanderbilt graduate student Laura Colbran found that Neandertal versions of FOXP2 would have pumped out much less of its protein than is expressed in modern brains. A rare mutation that causes members of a family to produce half the usual amount of FOXP2 protein also triggered severe speech defects, notes Simon Fisher, director of the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, who discovered the gene. Boosting FOXP2 expression may have been key to modern human language, he says.

http://science.sciencemag.org/content/358/6362/431.full

Genetic studies like these could help determine the important features of the human genome that make us uniquely human versus other hominids.

 

[rootone]

Only if you buy a ticket.

Cheers

Well parasites and viruses depend on robbing your ticket, but let's not get too complicated