"This is the first study of its kind to find discrete evidence that our need to bond with others, actually increases our openness to engaging in homosexual behavior." The comma here is a mistake. There should be no comma. I will try to rephrase this sentence to maybe help clarify: The study found evidence that demonstrates that our need for bonding will increase our willingness to engage in homosexual behavior.

I understand your explanation!!!!! Thank you so much.

In this sentence the word "that" joins two statements together. Here is a complete sentence which is grammatically correct: "our need to bond with others actually increases our openness to engaging in homosexual behavior". Here is another sentence which is grammatically correct: "This is the first study of its kind to find discrete evidence of this". We can use two different sentences (in that order), or we can swap the order and join them together into one sentence, using the word "that" to join them. Here is another example of the word "that" inside a much simpler sentence: "I found out that computers use a lot of electricity". I am not an English teacher, sorry, so my explanation is not very good, but hopefully this helps!

A part of the article: Well, according to new research published in the journal Archives of Sexual Behavior, it may have evolved in order to promote social bonding amongst humans. This is the first study of its kind to find discrete evidence that our need to bond with others, actually increases our openness to engaging in homosexual behavior. For their study, a team of researchers from the University of Portsmouth looked at the relationship between sexual attitudes and the hormone progesterone. What they discovered, is that the more progesterone there is in a heterosexual woman’s saliva, the more open she is to the idea of engaging in homosexual behaviour. Likewise, heterosexual men who are subtly reminded about the importance of having male comrades, reported feeling more open towards engaging in homosexual behaviour - and that was particularly true for men with higher levels of progesterone.

It's not a complete sentence, it's a mistake. Here are examples of possible completed versions of the sentence: This is the first study of its kind to find discrete evidence that our need to bond with others... ...is fundamental. ...is overstated. ...comes from our evolutionary past.