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2.2: Key Developments In Understanding the Origin Of Life On Earth

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    Key Developments In Understanding the Origin Of Life On Earth

    Carl Linnaeus was a Swedish botanist, physician, and zoologist (lived 1707-1778), who laid the foundations for the modern scheme of binomial nomenclature. Lineaus is considered a founder of modern taxonomy and ecology (Figure 2.2). For instance, humans are called Homo sapiens in binomial nomenclature.

    Carl Linnaeus
    Figure 2.2. Carl Linnaeus (1707-1778) is considered founder of modern taxonomy and ecology.

    Linnaeus's system of classification grouped organisms based on shared characteristics. Modern taxonomy attempts to connect taxonomy to the evolutionary framework of shared common ancestors (commonly referred to as the evolutionary tree of life). In the past three centuries, millions of species have been identified and classified, but the lineages of different species are constantly being revised as new information becomes available.

    Charles Darwin (1809-1882), a scientist/explorer, is credited with presenting the first published work dedicated to natural selection in his book entitled Origin of Species (published in 1859) (Figure 2.3). Darwin's theory on natural selection is now considered among be the main processes that brings about biological evolution. Darwin's book is a compilation of his observations and thoughts about plants, animals, and fossils initially gathered during a five-year voyage around the world studying nature onboard the Royal Navy ship, the HMS Beagle. Natural selection is the processes whereby organisms that are better adapted to their environment tend to survive and produce more offspring. Note: Darwin did not release his research for nearly two decades after the expedition largely out of fear of repression, but his work arguably became one of the world's greatest scientific works of modern times.

    Charles Darwin (Smithsonian Institution drawing)
    Figure 2.3. Explorer, Charles Darwin (1809–1882) published his theory of natural selection in a book titled Origin of Species in 1859.

    Gregor Johann Mendel (1822-1884) was an Austrian geneticist/researcher (and monk) who conducted experimental research on creating hybrids of garden peas. In 1865 and 1866, he published his research on how hereditary characteristics are passed from parent organisms to their offspring. Mendelian Theory is fundamental to much of what is known about modern genetics theories (Figure 2.4).

    Over the past two centuries, many scientific discoveries and technological innovations have advanced our knowledge of biochemistry, cell structure and processes, and genetic evolution. In 1951, James Watson and Francis Crick discovered and reported the double helical structure of the DNA molecule (Figure 2.5). Today, the entire genetic structure of human DNA has been mapped and reported via the Human Genome Project (2001). Genome mapping is now central to many kinds of biological and medical research.

    Mendel genetic variation DNA illustrated
    Figure 2.4. Statistical genetic variation illustrated by Mendel's research (applied to cats). Figure 2.5. DNA occurs within chromosomes within a cell nucleus (illustrated).