[10] He obtained a Licenciatura in biology, with a zoology concentration, from the Universitat de Barcelona,[11] in 1977, while working as a scientist in several institutions and as science writer for several printed, radio, and TV media.

He became dean of the George and Mildred Weissman School of Arts and Sciences at Baruch College/City University of New York, effective July 2016,[13] and stepped down in June 2020.

[14] While an undergraduate student in biology at the Universitat de Barcelona in Spain, Romero volunteered at the Museum of Zoology (later renamed as Museum of Natural Sciences) where he created the Hydrobiology Section [15] led a group of other undergraduates to work on aquatic organisms reorganizing some of the collections and re-identifying some of the mislabeled specimens.

He also volunteered working at the Museum of Geology of the Seminario Conciliar of Barcelona where he described several new species of Middle Triassic (240-235 million years old) horseshoe crabs and a set of fossils that he described as an entirely new group (subphylum) of animals never reported to science before.

Through these studies he was the first to propose that colonization of cave environments was an active process via behavioral adaptations preceding morphological ones (e.g. blindness and depigmentation).

This challenged the typological view of all cave creatures as completely differentiated from a genetic viewpoint from their surface (epigean) ancestors.

According to Romero all what was needed for the evolution of drastically morphologically distinct cave species were just a few changes in the genes controlling the development of features such as eyes and pigmentation.

One of those allowed him to discover that the first animal population depleted by Europeans in the American continent was of a pearl oyster species (Pinctada imbricata) off the coast of Venezuela.

Through his work he concluded that the initial resistance by French biologists to accept Charles Darwin's ideas was a combination of catholic mysticism and nationalism.

[35] In another study he concluded that environmental classification and intellectual inertia delayed for centuries the acceptance of whales and dolphins as mammals, instead of being considered fish.

[36] He has also worked on Darwin's life and published an analysis on how the British scientist was modifying his home at Downe, Kent, in order to accommodate to his scientific interests, his growing family and number of servants, as well as his health problems.

[37] Romero has promoted public understanding of science and the liberal arts, from hosting radio and TV shows, to producing documentaries.