Two fascinating truths about human nature: Why all embryos are initially female and how 'paralysis' helps us think deeply

The human body still remains a mystery, even in the context of remarkable advances in medicine. There are amazing aspects, such as the fact that during the first six weeks of intrauterine life, all embryos have female characteristics. In addition, the brain continues to raise the most unanswered questions in science.

Pregnant woman PHOTO shutterstock

Medicine has evolved incredibly especially in the last decades. Many diseases have been treated, new ones have been identified and questions asked for centuries have been answered. However, the human body and its development still hide mysteries for science. That is, we have organs, behaviors or different functions that even today medicine cannot fully understand or explain. At the same time there are discoveries that would cause astonishment, especially regarding the development of the human being in the mother's womb.

A world of girls

A particularly interesting medical discovery can also be included in the chapter of mysteries of the human being. Namely the fact that by conception, we are all initially girls. Or more precisely, all the embryos in the mother's womb begin to travel the path of development towards womanhood. Only later, after a few weeks of pregnancy, will they acquire the Y chromosome, specific to boys. Specialists say that for more than a month, all embryos, whether destined to be male or female, grow in a way that looks exactly the same. They look like their mother.

“This is natural, because she provides the vast majority of the supporting structure in which they grow. The egg's cytoplasm, a complex pool of essential nutrients; the mitochondria, the biological engines that provide the energy of life; and the uterus, the incubator in which the embryo begins to thrive – all are provided by the mother. At this stage of development, the father provided his DNA, a sliver of cytoplasm, a structure called a centrosome – which is necessary for the fertilized egg to cell divides – and, at the point of sperm penetration, the reference point around which the left and right sides of the body will eventually form”states Alexander Tsiaras in “The Invision Guide to Sexual Health”.

The same author states that during the first six weeks, the embryos look the same, even preparing to become girls. Absolutely everyone. Afterwards, the Y chromosome must “signal” correctly and be accepted. “Adam may be created first in the Bible, but Eve is the original child in every womb. All embryos, male (XY) or female (XX), begin the developmental path to womanhood, and in the first six weeks of growth they look exactly the same. For a boy to form, the Y chromosome must not only send the correct chemical signals to the brain and body, but these signals must be received correctly.”it is specified in the same work.

The same is supported by other specialists who show that sexual differentiation between fetuses occurs later in pregnancy and that at first we all look the same. In addition, all features and genitalia are phenotypically female.

“All human individuals—whether they have an XX chromosome, an XY, or an atypical combination of sex chromosomes—begin development from the same starting point. During early development, the fetal gonads remain undifferentiated; that is, all fetal genitalia are the same and phenotypically female. However, after about 6 to 7 weeks of gestation, the expression of a gene on the Y chromosome induces changes that lead to the development of the testes. Through therefore, this gene is extremely important in inducing testis development”says in “Exploring the Biological Contributions to Human Health: Does Sex Matter?” published by the National Academies Press.

The same study shows that testosterone production, if the Y chromosome is received and accepted, begins only at 9 weeks, resulting in the development of the reproductive tract and the masculinization (normal development of male sexual characteristics) of the brain and genitals.

The world of dreams, an impenetrable realm

Dreaming is a very well-known and seemingly trivial process that everyone knows and experiences very often. However, it represents one of the most mysterious human behaviors and functions. No one really knows why we dream and how it happens. Actually, at the moment, it is known that dreams occur in a certain phase of sleep and appear, in the brain, in the visual area of ​​the primary cortex, at least as shown by the studies of Sicarli or Solms, that is, in a portion located in the occipital lobe that receives information from the lateral geniculate nuclei.

Especially when they are in the REM stage, about 90 minutes after a person falls asleep. Dreams can be images, sensations, thoughts, emotions. They can be beautiful or nightmares that seem real. “The experience of dreaming is often similar to reality, and brain activity during REM sleep is similar to the state of consciousness. Since 1950, REM sleep has been considered the only stage that can generate dreams”show Xiao Lin, Ying Han and Lin Lu, in the work “Unraveling the mystery of dreams”.

Studies show that the brain actually prepares the whole body for dreaming. More precisely, certain neurotransmitters block the motor signals from the brain to the body inducing a state of paralysis – precisely to protect us. Without this state of paralysis, we would simply physically perform all the actions that occur during dreams. That is, we would wake up running in our sleep, or doing all kinds of unwanted actions. For the rest, research continues to identify the mechanisms that produce dreams and, ultimately, what they represent. Over time, however, there have been numerous theories that have tried to provide an answer to the question: why do we dream?

For some specialists, dreams are wishes and aspirations from the subconscious, for others they are simply random interpretations of signals from the brain and body in general. As Freud speculated, dreams reveal the deepest desires, hidden while we are conscious and which we do not have the courage to express.

For example, in his famous book “The Interpretation of Dreams” Freud advanced the idea that for us dreams actually represent unfulfilled wishes. In other words, we dream of things we can't have and want. Freud also said that dreams are full of hidden meanings and tried to decipher them based on the way people thought or behaved in the state of consciousness. For his part, the famous neuro-psychiatrist Carl Jung, who also worked for a while with Freud, developed a series of theories about dreams.

Jung believed that dreams actually provide solutions to problems we have when we are conscious. Or that they give us information about ourselves or about our relationship with other people, like repressed feelings in the subconscious that appear with dreaming. Definite, unequivocal explanations have not been found to date.

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