Scientists from Rotterdam

Ambrosius Arnold Willem Hubrecht (2 March 1853, in Rotterdam – 21 March 1915, in Utrecht) was a Dutch zoologist.
Hubrecht studied zoology at Utrecht University with Harting and Donders, for periods joining Selenka in Leiden and later Erlangen, and Gegenbauer in Heidelberg. He graduated magna cum laude with Harting in 1874 with a study on nemertine worms. In 1875–1882 he worked at the Rijksmuseum van Natuurlijke Historie in Leiden, where he was the curator of ichthyology and herpetology, and in 1882 became professor at Utrecht. In 1890–1891 he traveled in Java, Sumatra, and Borneo, where he made embryological studies, notably on the tarsier. He visited the United States in 1896 and 1907. Honorary degrees were conferred on him by Princeton University, the University of St Andrews, the University of Dublin, the University of Glasgow (LL.D 1901), and the University of Giessen.
Hubrecht´s most important work was in embryology and placentation of the mammals. In papers in the Quarterly Journal of Microscopial Science in 1883 and 1887 he put forth the theory—also held by Sir E. Ray Lankester—that the vertebrates originated in a Nemertine form, basing this on his discovery in the Nemertines of a continuous nerve sheath. The Descent of the Primates (1897) is the title under which were published his lectures at the sesquicentennial celebration at Princeton.
In 1883 he became member of the Royal Netherlands Academy of Arts and Sciences. Hubrecht founded the Institut Internationale d'Embryologie, today known as the International Society of Developmental Biologists.

Luitzen Egbertus Jan "Bertus" Brouwer (27 February 1881 – 2 December 1966) was a Dutch mathematician and philosopher who worked in topology, set theory, measure theory and complex analysis. He is seen as one of the founders of modern topology, in particular through his establishing the fixed-point theorem and the topological invariance of dimension.Brouwer also became a major figure in the philosophy of intuitionism, a constructivist school of mathematics which argues that math is a cognitive construct rather than a type of objective truth. This position led to the Brouwer–Hilbert controversy, in which Brouwer sparred with his formalist colleague David Hilbert. Brouwer's ideas were subsequently taken up by his student Arend Heyting and Hilbert's former student Hermann Weyl. In addition to his mathematical work, Brouwer also published the short philosophical tract Life, Art, and Mysticism (1905).