No one would ever have been able to predict that today, humanity would successfully undergo a species wide, mass evolution, in real time. So obviously not a single person was fully prepared for it, nor knew exactly how to deal with it.
What started out as your normal average Tuesday, quickly turned into global chaos as every single person in existence, underwent a drastic change. The mass evolution happened in stages. First, starting by eliminating all heman males by turning them all into females. This alone through scientists and governments into a crisis as the threat of human extinction now was a realistic concern. Even all of the stored sperm in sperm banks had been converted into human eggs.
An hour later, the second phase hit, and hit hard. With the human population now 100% female, the species as a whole suddenly restructured its entire means of reproduction. The human reproductive system became fully capable of accepting the genetic information from literally any male creature in the animal kingdom, as well as many species belonging to the plant biological kingdom as long as it produces a fruit or vegetable, nut, or grain.
In order to accomplish this, the human female developed a means to integrate various traits from their desired mate's species onto themselves, modifying their physical appearance if need be. Their offspring will be a hybridization of the parents, but will be genetically stabilized to only be able to breed with human females and the offspring's paternal species.
For example. A woman and a bull become mates. The woman will develop some cow traits, such as growing an udder, a tail, horns, hooves, dark/light patches, cow ears, etc. Their child will be a human/cow hybrid from birth and can be either male, female, or both. Some can even change their sex at will in some cases, but only with a few specific father species.
The human/cow hybrid offspring will only be able to reproduce using either a cow, a human/cow hybrid of the opposite sex, or a pure human female if they are born male. If the offspring is female, they only can reproduce with either a male human/cow hybrid, or a bull.
Polygamy also instantly became the standard, instinctivly. Many human females, especially those who were in a relationship at the time, choose to stay together and find a mate whom which they could share.
The last phase was far simpler than the other two, and nearly altered the opinion on some human concepts. Things such as the desire to wear clothing was reduced heavily unless it was necessary for survival. Using silverware to eat became second to just eating using only hands and teeth. Bowls became the most preferred vessel for food in an instant, though many just took to grazing if they had a mate in mind that was a herbivore. Quite a few still farmed and processed food, though now shape and appearance were not as important as taste and nutritional value.
This day became officially known as the first day of the last days of pure humanity.