Tuesday was Abraham Lincoln's 199th birthday. And Charles Darwin's too.

Darwin is perhaps best known for his theory of natural selection borne from his meticulous observations of nature synthesized with the published works of numerous other scientists. Lesser known to many is the fact that Darwin's interest in nature and science was ignited during his youth by his fascination for insects, especially beetles.

In 1819, when he was just 10, young Darwin took his first notice of insects along the coast of Wales. He noted that many of the species he encountered were different from those found near his home in Shropshire. It was this recognition of species and place that sparked his lifelong quest to understand how nature +works.

While attending the University of Cambridge (1828-1831), Darwin spent much of his free time scouring the nearby countryside for beetles, undertaking collecting trips with friends, and visiting the notable British entomologists of his day.

Darwin's indefatigable interest in beetles brought him to the attention of John Steven Henslow, professor of botany. Henslow possessed an extensive knowledge of entomology and many other natural history subjects. His relationship with Darwin was instrumental in broadening the young naturalist's approach to the study of natural history.

Darwin so impressed Henslow on their collecting forays with other Cambridge students that the professor recommended him for the position of ship's naturalist on the H.M.S. Beagle. Charged with gathering specimens of all sorts, Darwin's efforts went well beyond insect collecting. From 1831 to 1836, he amassed an impressive collection of plants, animals and minerals from around the southern half of the world.

Upon his return, Darwin discovered that his insect specimens were mostly unwanted by major museums and universities. As a result, Darwin's insect collection was divvied up among several specialists.

Many of his specimens are now scattered among London's University of Cambridge, Oxford University and The Natural History Museum, as well as the National Museum of Ireland and elsewhere.

Despite his interest in beetles in particular, Darwin never published papers on their classification. However, the official report on the voyage of the Beagle is replete with observations of insect behavior.

His monumental works "Origin of Species" and "The Descent of Man and Selection in Relation to Sex" are filled with strong insect-related themes. "The Various Contrivances by which Orchids are Fertilised by Insects," "Insectivorous Plants," and several other papers dealing with pollination are also filled with examples drawn from the insect world.

Today, just as in Darwin's day, insects remain a fertile field of investigation for scientists studying a broad range of biological phenomena. And like Darwin, scientists who support their ideas with disparate facts drawn from around the world are most likely to make the greatest contributions to our understanding of the world.