So, What’s the Verdict? A Girl or a Boy?

A girl or a boy, perhaps? is usually always the first query people ask when they see a woman pregnant with her first child and her noticeable baby belly. Now, because we are familiar with our own human biology, there are some presumptions that go along with that question that we take for granted. We assume that there is a 50/50 likelihood of either answer, male or girl, for human infants.

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Why Is There Only Two Genders? The Answer Might Surprise You

However, why is it this way? The system that our species has developed to determine sex will determine the answer. You see, the XY chromosome system uses genetics to determine a baby’s sex for the majority of mammals. Mammals have two sex chromosomes, one inherited from the mother and one from the father. We get a girl when we have two Xs, and a male when we have an X and a Y together. The father determines the sex, and there is a 50/50 possibility of creating a male or female because men can pass either an X or a Y in their sperm cells whereas females can only pass on Xs in their egg cells.

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The Tree of Life: Why Some Systems Work Better for Some Species

Although this system has served mammals well, there are other systems that have served other species just as well across the tree of life. Other animal species also have genetic sex determination, albeit these species’ methods can vary greatly from ours. In some reptiles and birds, the sex is genetically determined, however in these animals, the sex is determined by the mother rather than the father. These males only have Zs to donate since in those groups, a man is produced by a pair of Z sex chromosomes. However, in these animals, pairing up one Z and one W chromosome results in a female. It simply depends on whether mom inserts a Z or a W into her egg that determines whether there will be a male or female in this system.

Ants Have a Most Intriguing Process for Identifying Sex

Some societies have seen genetic sex determination entirely differently. If you are a male ant, for instance, you do not have a father since ants have one of the most intriguing processes for identifying sex. Work is divided dramatically in an ant colony. A queen and a small group of male reproductive workers are present, along with soldiers who guard the colony and workers who gather food, clean the nest, and look after the young. The queen will now mate and collect the males’ sperm to store. The system really starts to get intriguing at this point. The egg will develop into a female if the queen utilises the sperm she has saved to fertilise it. However, if she lays an egg without fertilising it, the resulting ant will always be a male even though it will still develop into an adult. So as you can see, male ants cannot have fathers. And male ants live this way, having only one copy of each gene, making them resemble walking sex cells. We observe this system, known as a haplodiploid system, in ants as well as other highly social insects like bees and wasps.

The Truth About Animal Offspring Sex

Since our own sex is genetically decided and we are aware of other animals whose sex is also genetically determined, it is natural to infer that all animals’ offspring’s sex is also genetically determined. The question of whether an animal will have a boy or a girl, however, can depend on factors like the weather and has nothing to do with a person’s genes. These creatures resemble turtles in general and alligators. The temperature in a developing egg determines the sex of an embryo in these species. In these animals, the sex of the foetus is not yet known at the moment the egg is placed, and it is not known until a critical period in the middle of the overall development period. And at this moment, the temperature in the nest entirely determines the sex. For example, in painted turtles, warm temperatures over the critical temperature result in the development of females within the eggs, while chilly temperatures result in the development of males.

Painted turtles are all hot females and cold males

You can keep in mind that painted turtles are all hot females and cold males—I’m not sure who came up with this mnemonic. Some tropical fish don’t decide whether they’re having a boy or a girl until even later in life. You see, all clownfish begin life as boys, but as they get older, they change into females. Additionally, they live in small groups with a clear hierarchy of power, where only the most dominant male and female can procreate. Amazingly, if the group’s dominant female passes away, the biggest and most powerful male will immediately change into a female, take her place, and all other males will advance one position in the hierarchy.

How Sex is Determined in the Green Spoon Worm

The sex of the young is determined by an entirely different component of the environment in the green Spoon worm, another quite different aquatic species. It merely depends on where a larva happens to fall at random on the ocean floor for this species. A larva will mature into a female if it touches the surface of the open ocean. However, if it touches a female, it will change into a man. Genetics thus provides a solution to the question of boy or girl for some animals. Others find their solution in their surroundings. And for yet other people, they don’t even think of asking the question. Think about whiptail lizards, for instance. The solution is simple for those desert lizards. It’s a female. Always a female. Since they are a largely female species, when eggs hatch, they produce female clones of themselves.

Is It a Boy or a Girl? How the Sex Determination Mechanism Works

So, is it going to be a boy or a girl? Really, everything in the animal kingdom is determined by the sex determination mechanism. That system is an XY genetic system for humans.

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Complicated Sex Determination Process: You Might be Surprised