We live in a world where there is a lot of discussion on gender. People have opinions and they certainly don't agree on all of those opinions, but science often steps in to clear things for us.

In part, researchers may talk about biological sex and how we have reproductive organs that make us either male or female. Genetics is another way that sex is demonstrated in nature, and this understanding has really only come about in recent years.

Photo: Pixabay/Michael

Then we have certain species in the natural world that seemed to break out of the mold. For example, there are species that change their sex as they get older, and other animals may just make us scratch our heads and wonder.

According to a report in the journal Current Biology, the white-throated sparrow is in a class of its own. They may just have up to 4 different genotypes or distinct sexes.

The white-throated sparrow (Zonotrichia albicollis) has different subspecies. White males don't tend to take care of the offspring, but tan males will take care of the offspring and are monogamous. The female sparrows will either care for the young or continue with mating efforts.

Photo: Pixabay/No-longer-here

White and tan striped sparrows typically mate with other sparrows with the opposite coloring. The white-striped birds have a mutated gene that seems to be a new type of chromosome.

According to the report, that chromosome does not allow the genetic material of one bird to be exchanged with its mate. This was actually discovered in the 1960s by scientists who found that tan birds have two chromosomes that are identical. On the other hand, white birds have one inverted and one regular chromosome.

When a white and tan sparrow mate, there is a 50% chance that an inverted gene will be inherited.

Photo: Pixabay/Michael

Elaina Tuttle and Rusty Gonser are researchers who are married to each other, and they did some study on the subject in the early 2000s. They discovered the gene was mixed up rather than just being flipped.

According to an evolutionary ecologist, Catherine Peichel, the birds are an "amazing system."

According to Nature, she went on to say: "The process of sex-chromosome evolution tends to erase much of the evidence of how it happened, so being able to watch the process in action is a huge benefit."

Photo: Pixabay/Michael

Tuttle made some fascinating discoveries before she passed away in 2016. It seems as if they have four sexes rather than two.

Another evolutionary biologist who worked with Tuttle, Christopher Balkrishnan said: "One individual can only mate with one-quarter of the population. There are very few sexual systems with more than two sexes."

It is not uncommon for certain species to have multiple sexes. Being able to study these sparrows, however, has shed some interesting light on the subject.