The title et al I have found the extension "et al" with biologists from different nationalities like : Avery et al ; Taylor et al etc. My question : 1\. What does it mean? 2\. Why only biologists?

The Latin phrase _et alia_ (abbreviated et al.) means **and others**.

It is not limited to biologists, nor those of different nationalities. If I refer to this computer graphics article, I can refer to it as "the paper written by Henrik Jensen, et al., regarding physically based modeling of fire..."

Note that the expansion of et al. can also be _et alii_ and _et aliae_ , which are the masculine and feminine forms, respectively; _et alia_ is the neuter form.