“Life makes its way”. With this sentence, the mathematician Ian Malcolm launched in the first part of jurassic-park a premonition of what was to come. He uttered it after being informed of the birth control mechanism of the creatures in the park. All dinosaurs were female. However, in the end some managed to procreate. In previous installments of Jurassic World We have seen numerous times that history repeats itself and, how could it be otherwise, it does so in this sense as well. There is no more to see how Bluethe most iconic of the female velociraptors in this second saga, manages to bring another creature into the world in Jurassic World: Dominion. But how does he do it? The key is in parthenogenesis.
Logically, these films are full of fiction, but their plot also has phenomena that can be explained by science. And this is one of them. In fact, it is not uncommon in the wild for some females to bring young into the world in the absence of a male.
Although the process of parthenogenesis is more common in invertebrates, it can also occur in vertebrates such as reptiles or birds. Talking about reptiles and birds leads us to think of dinosaurs, so it is more than likely that Blue’s motherhood in Jurassic World: Dominion is due to this phenomenon. In the movie they don’t get to say it, but the truth is that everything fits.
What is parthenogenesis?
Parthenogenesis is a phenomenon by which female sex cells can develop no need for fertilization to give rise to a new individual. In short, it consists of a punctual process of asexual reproduction in species that normally reproduce sexually. It is still a way of perpetuating the species in unfavorable situations in which females cannot access a male (or do not want to).
In recent years, numerous cases have been reported in vertebrates. One of the most curious was Charlie, a female Komodo dragon that managed to lay three eggs without ever having sex with a male. Her case is quite exceptional because she did come into contact with a male at the zoo where she lives. However, she didn’t seem to feel like getting along with him and she eventually ended up developing this procedure that normally occurs in extreme cases.
Cases have also recently been documented in a female shark and an anaconda. Sometimes it is just one baby, while at other times there are several. In Blue’s case, in Jurassic Worldbrought forth a single daughter, whom they baptize as Beta. But what else can we know about her assuming that she was born by parthenogenesis?
Life makes its way in ‘Jurassic World’
Animals that normally reproduce sexually have a variable but always even number of chromosomes in their somatic cells. That is, in cells that are not sexual. In the sexual ones (eggs and sperm) they have half, so that when fertilization occurs and they give rise to a zygote, I have all the chromosomes of the somatic cells.
For example, humans have 46 chromosomes. In eggs and sperm there are 23 and 23, so that after fertilization we have a zygote of 46 chromosomes that will divide into cells with the same endowment. However, what happens with parthenogenesis is that the female contributes a chromosome, as is normal, and then duplicates it. Thus, she will not need another given by a male.
Regarding the sex chromosomes, in humans the female sex is associated with XX and the male with XY, so that lEggs can only carry X chromosomes and sperm either X chromosome or Y chromosome.
Now, what would happen if we humans could reproduce by parthenogenesis? Basically, that in that case we could only have daughters; since, by not intervening a male, there would never be Y chromosomes.
In other animals it is different. For example, in the case of Komodo dragons the chromosomes are different. Females are WZ, while males are ZZ. This would result in ZZ or WW offspring. It could never be WZ, because we have said that the female contributes a single chromosome and this is duplicated. The problem is that WWs don’t exist, it would be like YY in humans. Therefore, they do not go ahead and do not become young. Therefore, there could only be ZZ males. This is what happened to Charlie, whose eggs hatched three males: Onyx, Jasper and Flint.
As for what happens with Blue in Jurassic World, we do not know exactly what reproduction would be like in dinosaurs, although there are certain assumptions. For example, in 2004 a review was published in which Two possibilities were considered: genetic sex determination and environmental sex determination. The first is the one that governs the chromosomes and can be seen in animals such as our own komodo dragons. As for the second, which occurs in crocodiles and some turtles, is mediated by temperature. Depending on what temperature the eggs are incubated, the individual that hatches from them will be male or female. This can generate a great inequality marked by the prevailing temperatures that could even end the decline of a species.
Assuming that the dinosaurs of Jurassic World If they had a genetic determination of sex, the distribution of chromosomes could be similar to that of the Komodo dragon. Therefore, by parthenogenesis Beta should have been a male. But there could also be an environmental determination, in which case it could be female. The problem is that if the determination were environmental, life would have made its way much sooner than it did, both in jurassic-park like in Jurassic World. Let’s say that there is a bit of fiction here. It’s normal, after all, it’s still a movie. Be that as it may, the case of Beta is a good example that Ian Malcom was right: life makes its way. And he does it both in the two dinosaur parks and in real life.