First animals to ever have sex were not what you would have expected

There are several ways in which living organisms on Earth reproduce, and sex is just one of the methods. Some reproduce by simply splitting themselves in twos and fours, and some do not need a partner to reproduce at all. So, have you ever wondered, which were the animals that were the first ever to usesex as a method for reproduction?

Humans? No. Some other mammals? no again. Birds and bees? Nah.

Scientists have been fascinated by the question, and had posited that sexual reproduction existed since animals came into being on planet Earth, which is around 800 million years ago.

Add WION as a Preferred Source

And probably the first to use sexual reproductionare, wait for it, sponges.

The relatives of our humble bathroom sponge lived in the ocean, and some spunge species could reproduce sexually. But wait, how did scientists reach the conclusion that they were the first animals known to use sex for reproduction?

In 2021, it was reported that scientists had identified the oldest fossil ever recorded. It was of a sponge, dating back at least 890 million years. Recovered fromNorthwest Territories of Canada, they were classified as part ofkeratose demosponges, or horny sponges. The sponges are known to reproduce both sexually and asexually.

Their sexual reproduction, though, is done in a rather 'detached manner': sperm and eggs are released into water, which then combine to form new organisms.

Actual sexual intercourse or copulation for reproduction is thought to have been used for the first time by some types of fish, according to an article in LiveScience.

"Microbrachius dicki" is one such fish, said Long, who wroteThe Dawn of the Deed: The Prehistoric Origins of Sex.Microbrachius dicki males used claspers to inseminate females internally and the females had "reciprocal genital plates," as revealed in fossils, according to LiveScience.

But wait, the story is not over. Even before animals existed in their varied and full-fledged form, sexual reproduction was happening, when we change the definition not to include actual copulation.

That was done through a process called meiosis. Meoisois is defined by the National Human Genome Research Institute of the US as "a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes (the sex cells, or egg and sperm)."

Watch: Visuals of protesters looting things, lying on Sheikh Hasina's bed in her residence go viral

This form of meiosis was present in several eukaryotes. Now, what are eukaryotes?

We are all eukaryotes: from fungi to plants to animals, basically every organism with a nucleus in their cells.

The first eukaryotes to have meisois as a process of reproduction- meaning sexual reproduction- may have existed some 2 billion years ago in the form of bacteria, said the LiveScience article

(With inputs from agencies)