Karl Kessler

Karl Fedorovich Kessler (19 November 1815 – 3 March 1881) was a Baltic German zoologist who worked as a professor of biology at Saint Petersburg Imperial University.

In 1837, Kessler and his botanist friend from student days, Nikolai Zheleznov [ru] went on an expedition to Finland.

He then obtained a zoology chair at the University of Kyiv, a position vacated by Alexander von Middendorff who went to Siberia on an expedition.

He also studied the fish of the Dniester, Dnieper, and Southern Bug rivers, and on the Ukrainian coast of the Black Sea.

The anarchist Peter Kropotkin later developed this theory in his book Mutual Aid: A Factor of Evolution.