====== Number of species ======

>We demonstrate that after more than six decades, estimates of global species richness have failed to converge, remain highly uncertain, and in many cases, are logically inconsistent." \\ \\ Source :   [[http://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(14)00026-3|Global species richness estimates have not converged]] for //Trends in Ecology & Evolution.//

The paper cited above looked at the estimates for total land and marine animal species -  which varied from 0.5 million to 10 million species.

A 2015 paper in the journal //Proceedings of the National Academy of Sciences// (using mathematical scaling-law methods to predict likely microbial species numbers) found that :

>Using this scaling law combined with the lognormal model of biodiversity, we predict that Earth is home to as many as 1 trillion (10<sup>12</sup>) microbial species."  \\ \\ See [[http://www.pnas.org/content/113/21/5970.abstract|Scaling laws predict global microbial diversity]] //PNAS// 113 (21) 5970-5975;

Current estimates are that, at best, only a tiny fraction of species on Earth have so far been properly catalogued and described.

=== Example : ===

 A set of 2017 experiments at Stanford University, US, found that  [[https://med.stanford.edu/news/all-news/2017/09/nearly-all-the-microbes-inside-us-unknown-to-science.html|"Nearly all microbes inside us unknown to science"]]

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Also see [[content:life_sciences:life_itself:species_definition]]

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