Every person and animal starts out female. This why there is an equivalent for each sex organ.

You may find this book helpful. Page 533 is the start of the chapter on sex and the brain, and page 549 specifically states that the change from female to male gonads in development involves the release of androgens, which then begin the process of the masculinisation of the brain via gene expression. In the absence of these androgens, different gene expressions lead to the feminisation of the brain.

We actually have two brains. One surrounds our heart. It is the first organ to form after the heart and remains in place throughout our entire lives. It is connected to our head brain, and I theorize it to be directly responsible for initiating thought and speech from the ncRNA.

Yes that’s true, that’s why men have nipples :D

Keep in mind that “hormones” and “genes” are two very broad categories. Growth hormones and genes responsible for development cause the brain to grow and form in the first place, and sex hormones, produced under instructions coming from the sex chromosomes, differentiate the brain and the rest of the body. You are correct in understanding that sexual differentiation happens after development has already begun.

The wikipedia article on sexual differentiation has a detailed timeline of how and when human fetuses become masculinized and feminized. In short, sex hormones do not seem to start to take effect in the body until around the 8th week of gestation.

You asked, “so that’s to say there’s no differences between the sexes’ brains before the sexual identity is determined???” I think it would be tough to argue that there is a point “before the sexual identity is determined” since this is (arguably) determined by which chromosomes you start with, XX or XY. Of course, this invites the question of what exactly constitutes “sexual identity”—is it defined solely by chromosomes, or do maleness and femaleness depend on hormones, secondary sexual characteristics, the presence of sex-determining genes like SRY, the formation of genitalia…? But I don’t think anyone has a definitive answer to that one.

@RealEyesRealizeRealLies: I am not aware of any evidence that neural cells innervating cardiac tissue have any relationship to any cognitive processes whatsoever. Speech is a reasonably well-understood phenomenon that involves specific cortical regions, most notably Broca’s area and Wernicke’s area. I also am not aware of any evidence suggesting ncRNA is uniquely involved in thought or speech.

@RealEyesRealizeRealLies Do you have a source? The cardiac plexus is solely responsible for cardiac function. To my knowledge, the only animals with a second brain were the sauropods.

@nikipedia @FireMadeFlesh

On the Brain in the Heart, two sources:

Neuroscientists have recently discovered exciting new information about the heart that makes us realize it’s far more complex than we’d ever imagined. Instead of simply pumping blood, it may actually direct and align many systems in the body so that they can function in harmony with one another. These scientists have found that the heart has its own independent nervous system – a complex system referred to as the brain in the heart. There are at least forty thousand neurons (nerve cells) in the heart – as many as are found in various subcortical centers of the brain.

AND

After extensive research, one of the early pioneers in neurocardiology, Dr. J. Andrew Armour, introduced the concept of a functional heart brain in 1991. His work revealed that the heart has a complex intrinsic nervous system that is sufficiently sophisticated to qualify as a little brain in its own right. The heart’s brain is an intricate network of several types of neurons, neurotransmitters, proteins and support cells like those found in the brain proper. Its elaborate circuitry enables it to act independently of the cranial brain – to learn, remember, and even feel and sense.
________

On Speech and ncRNA,

First, a bit of background. It was Noam Chomsky who first suggested the hypothesis of an innate syntactical structure Generative Grammar that must be present within human beings. I think we are beginning to actually discover this, and the research below satisfies his requirement for recursion.

“Chomsky has maintained that much of this knowledge is innate, implying that children need only learn certain parochial features of their native languages.[37] The innate body of linguistic knowledge is often termed Universal Grammar

Now Geoffrey Sampson is suggesting the same for Natural Semantics.

Come now the April 2010 issue of Nature Journal features the research of Wes Warren of Washington University Genome Sequencing Center.

Warren has demonstrated a different mechanism to explain language than mere interactions of neurons within the brain. He seems to have discovered what actually causes those interactions to occur.

“We show that song behaviour engages gene regulatory networks in the zebra finch brain, altering the expression of long non-coding RNAs, microRNAs, transcription factors and their targets. We also show evidence for rapid molecular evolution in the songbird lineage of genes that are regulated during song experience. These results indicate an active involvement of the genome in neural processes underlying vocal communication and identify potential genetic substrates for the evolution and regulation of this behavior.”

The implications of this are staggering, as “The zebra finch is an important model organism in several fields1, 2 with unique relevance to human neuroscience3, 4. Like other songbirds, the zebra finch communicates through learned vocalizations, an ability otherwise documented only in humans and a few other animals…”

We once again find another use for the so called Junk DNA. It seems that when the Zebra Finch expresses a DESIRE to sing, that desire causes a change in sequence of the “long non-coding RNAs, microRNAs, transcription factors and their targets.” And thereby, a change in that sequence, is the very mechanism which causes the “interactions of neurons within the brain”.

“Two of the cDNA clones that measured the most robust increases27 align to an unusually long (3 kilobases (kb)) 3′ untranslated region (UTR) in the human gene that encodes the NR4A3 transcription factor protein (Fig. 4a). The entire UTR is similar in humans and zebra finches, with several long segments of >80% identity”

“These findings indicate that this NR4A3 transcript element may function in both humans and songbirds to integrate many conserved microRNA regulatory pathways.”

“It has been proposed that ncRNAs have a contributing role in enabling or driving the evolution of greater complexity in humans and other complex eukaryotes32. Seeing that learned vocal communication itself is a phenomenon that has emerged only in some of the most complex organisms, perhaps ncRNAs are a nexus of this phenomenon.”

@RealEyesRealizeRealLies: I strongly suggest you learn about some basic biology—specifically, the central dogma of molecular biology in order to better understand the findings you reference.

I do not consider a for-profit website marketing essential oils nor a blog written by a lawyer to be useful sources for scientific research.

Sorry. If you’d like to buy the book, it’s $90. Basic and Clinical Neurocardiology.

And thanks for the suggestion to learn some basic biology. I actually extracted DNA no less than two hours ago. And what does the central dogma have to do with Warren’s research? What about this do you find troublesome?

@nikipedia “sex hormones do not seem to start to take effect in the body until around the 8th week of gestation.” can I interpret it as “all brains are female before the 8 week of gestation”?

@RealEyesRealizeRealLies sorry but I don’t get that….. what’s the correlation between Chomsky’s UG and Sexual identity?

@jesienne: Well, define what it means to be “female.”

Sorry cooking dinner and forgot about this @jesienne. I’m way off topic and out of line with my responses. I was simply attempting to provide more info to those who requested it. I should never have mentioned the speech implications on this thread. My apologies, for I am very much out of line here.

On sexual identity, please consider that the brain may have nothing whatsoever to do with determining that. @nikipedia is very correct to assert that gender is “determined by which chromosomes you start with, XX or XY”, before the brain even exists. Her further postulations are also very much worth considering.

It all starts with gene expressions which eventually also lead to the production of hormones.

@RealEyesRealizeRealLies Thanks for the information. I found it quite interesting, although I’m not entirely convinced.