Elizabeth Blackwell (February 3, 1821) was a medical doctor born in England, United Kingdom. As a teenager she immigrated with her family to the USA. Early in her career she opened a school for girls were she taught for a few years. After teaching in several other schools, she became interested in medicine and decided to go to medical school. Blackwell was denied entry to many medical schools because at that time medical schools accepted only men. Finally after applying to many institutions, she was accepted to a medical school, in Geneva New York. It was a difficult time of Blackwell; due to discrimination and harassment form her male peers and professors. However she was persistent and obtained top marks in her class, becoming the first woman to receive a medical degree in the USA. In order to obtain experience, she furthered her training in France and England for a couple of years before searching for a medical position in hospitals. Back in the States it was very difficult for her because no-body would hire her, so she opened her own practice that grew and eventually become a hospital; the New York Infirmary for Indigent Women and Children. This institution became the first medical college for women and become very successful in training nurses. Eventually Blackwell moved back to England were she opened a medical practice and lectured in medicine. She wrote several books and articles advancing the idea that hygiene is paramount to prevent disease.

Mary Leakey (February 6, 1913) was a British paleoanthropologist that discovered the fossils many early hominids and their artifacts in Africa. She started her career as an illustrator of archaeological digs, this prepared her for the future illustrations of her own diggings. She met the anthropologist Louis Leakey looking for a job to illustrate his archeological digs and became his wife and partner. She was a keen observant and very successful in finding hominid fossils. Mary Leakey’s two important early fossils, Proconsul africanus (Australopithecus Africanus) and Australopithecus boisei (Paranthropus bosei), showed that hominids were present in Africa 1.75 million years ago, long before what it was thought. She also found the remains of Homo habilis, called the tool user because of the associated tools found at Olduvai Gorge. Mary documented the Olduvai Gorge stone tools and followed their development through time showing how they progressively become more advanced. One of her most important contributions to hominid evolution was found South of the Gorge, in Laetoli, where Mary Leakey and her team found the footprints tracks of two hominids preserved in volcanic beads. This clearly showed that these hominids, about 3.5 million years ago, were bipedal and probably belonged to the genus Australopithecus. Mary un-earthed many other hominids and their artifacts during her career, after retirement from field work, she gave many lectures and published her findings.

Charles Darwin (February 12, 1809) was a British scientist, probably one the most famous biologists ever. He was always interested in science and during his early education took courses in geology and botany from eminent 18^th century scientists. When he was 22 years old, Darwin embarked in a lengthy trip aboard the HMS Beagle around the world. During this trip he used his previous scientific knowledge, keen observation, and detailed notes to start thinking and questioning how biological diversity is produced; how species are formed. He noticed that there were similarities in animals living in different places, like adjacent islands, and he hypothesized that these differences may be due to small changes in their environment, biogeography. He collected many fossils of extinct animals and noticed that they looked similar to extant (alive) animals suggesting to him that the earth is ever changing. When he went back to England he studied his specimens and with the expert knowledge of other scientist he came to the idea that new forms of animals replace old ones. Also he realized that the birds he collected in the Galapo’s Islands were not different animals but that they were all the same species; finches looking different because they were differently adapted. Darwin thought that evolution (change with time) has a mechanism and inspired by Malthus book in economics ‘Essay on the principle of population’ he proposed natural selection was the mechanism for evolution. For many years Darwin patiently worked to produced evidence to back up his theory and finally published his finding in his 1859 book ‘on the origin of the species by means of natural selection’. He wrote several other books, one of which  ‘the ascent of man’ was controversial because it suggested that man and animals share a common ancestor.

Agnes Arber (February 23, 1879) was a botanist born in London. Early in life, her artist father taught her to draw and illustrate plants. A skill that was very useful to her later, as a students and a scientist, to illustrate her own scientific publications and books. Her studies as well as her research always revolved around the study of plants. While attending the University of Cambridge, she studied the anatomy and morphology of gymnosperms. She wrote several books, all in different aspects of land and water plant morphology, anatomy, life cycles, and classification. Arber was the first woman to receive the Gold Medal of the Linnaean Society of London. Due to trying times during the Second World War, she had to close her botanical laboratory and stop doing research. During the later part of her career Arber produced several philosophical publications pondering on the unity of all living things.

Linus Pauling (February 28, 1901) was an American Chemist, and a very prolific scientist that won the Nobel Prize in 1954 and 1962. His main interests and were he focused most of his energies were on the study of the nature of the molecular bond and the physical structure of molecules. Pauling doctoral thesis was on determining structures of crystals by using X-rays, later he moved to use the more powerful technique of electron diffraction. These techniques allowed him to build an electro-negative scale measuring the power of atoms to attract electrons in a covalent bond. Further investigation into the nature of the molecular bond led Pauling to propose the concept of resonance to explain why the single and double bond in some structures like benzene have the same dimension. Later in his career he became interested on the structure of biological molecules like DNA and proteins. He worked on the structure of hemoglobin, and the nature of the interactions between antibodies and its antigens. In 1954 he was awarded the Nobel Prize for Chemistry for his contributions on the nature on the chemical bond and the determination of biological structures. The second Nobel Prize for peace was awarded to Pauling in 1962 for his efforts to ban nuclear weapons testing. Due in part to his efforts the nuclear ban test treaty was established. Pauling wrote many books and continued to work as a scientist.