I assume people are talking about the
Belyaev silver fox experiment?
I think people have a slight misconception about the biology and evolution of the brain. I don't feel like posting all the links I've posted in several other threads again and having them go unread, but I'll just say that in evolution, there is not really any such thing as equilibrium. Everything is in flux.
From reading this thread, I see people talk about whether humans are like animals in our personalities or whether our personalities are genetically 'determined' or whether we are a transitional species or not, and it makes me wonder how people think evolution actually works.
The way our brains are structured is dependent on genetic and epigenetic influences. Genetics will make different parts of the brain, which have been shown to be directly correlated with different cognitive processes, grow to different sizes, have differing concentrations of various glial cells, astrocytes, and synaptic junctions. Epigenetic (ie environmental and social constructivist) influences determine long term potentiation and other synaptic plasticity developments - it does this through DNA methylation and acetylation, protein ubiquitination and ADP ribosylation, genomic imprinting, histone tail modifications, and numerous other effects.
The point being, these are modifications to the way genetics are expressed, even if it comes from an external stimuli (like social constructivist and other interpersonal and intrapersonal ways of neural plasticity, or even our diets, environments, and sleep habits).
And in evolutionary terms, the idea of humans being 'smarter' is a bit misleading. When discussing evolution, an organism fits it's niche. There is no direction to evolution - as I said, it is always in flux. There is a regularly calculated amount of genetic mutation, most of which is neutral (there is a certain level of redundancy in the genetic code, with several possible codons being used for a single amino acid, allowing for some 'mistakes' without fucking the whole thing up), some being negative, and others simply being
different.
The latter one is the main point. No mutation is ever positive in itself, but only depending on the environment. Being a math or piano prodigy won't mean shit if you're born somewhere like Darfur or North Korea, and it certainly won't mean shit if you're lost out in the jungle where the so-called "lesser" animals like a chimpanzee will survive circles around us. Are humans transitional animals? Of course - there is no such thing as a plateau in evolution, even if there is a stagnant environment. But, if we undergo a sudden change in the environment, humans have enough genetic diversity that even if three fourths of our species goes extinct, those suitable to the new environment will survive and a new variety of genetics will arise.
Personality types are a variation in human genetics; that is what natural selection "acts" upon.
Comparing the personalities of humans and animals seems a bit bizarre to me. Sure, animals have different personalities among their own species and perhaps even genus, but the brain structure of say, a human and a dog, is so vastly different, having taken such different evolutionary paths, with such different selection pressures etc that it wouldn't even be a good "evolutionary idea" (for lack of a better term) for us to process information in the same ways.
The genetic determinism debate is a bit hackneyed. Anyone who thinks that something being biological meaning that it's a form of determinism only exposes themselves as being ignorant about how genetics and biology actually works, especially in an organism that is capable of introspection and self reflection (which, by the way, is a result of our biology).
Being human doesn't make us "break free" of our biology, and being biology ourselves doesn't doom us to a life of mindlessly eating, sleeping, and fucking, nor does it excuse us from acting like savages. If anything, evolutionary psychology and neuropsychology reveals to us why we process information in the ways we do and explains the urges we experience, which allows us to understand these parts of ourselves, being able to reflect on them, fix those aspects we want to fix and embrace the other parts (in others and ourselves). It's no different than just straight up MBTI theory, which doesn't constrain us to act a certain way, but allows us to apprehend what makes us tick - evolutionary psychology and neuropsychology simply lets us understand this from a physical, biological standpoint.
Sorry about the long post, but normally I would have supplemented it with links to make my points evident, but that generally isn't very effective.