From Jordana Cepelewicz at Quanta:
For over a century, distinctions between types of cells relied on how they appeared under a microscope: their shapes, sizes, locations and their uptake of staining dyes. Recent decades, however, witnessed a shift to molecular methods that use fluorescently labeled antibodies to target protein markers on the cell’s surface. Although this approach allowed researchers to isolate more cell types, it was not enough, according to Hacohen. Until 2009, biologists could analyze cells only in bulk, averaging signals from multitudes of them to get a picture of what was going on in a tissue. When sequencing RNA from individual cells finally became possible, the initial analyses were what Hacohen called “biased” and “shallow” because the few markers used to classify the cells were too insensitive to nuances of differences among them. “Does this really capture the complexity of the cell?” Hacohen said.
In a study published in Science this past April, he and his team showed that, as expected, much of this complexity had been obscured. Analyzing patterns of gene expression in individual human immune system cells, the researchers refined the definitions of the types known as dendritic cells and monocytes and identified a novel type that had been overlooked. Moreover, they discovered that a cell population thought to comprise one subtype was actually a mixture of two, which perform different functions.More.
Darwinism was a much more intellectually viable idea in the days when cells were simple little blobs of jelly. Now it hangs on by sheer determination and a killer instinct.
See also: Lungs’ unexpected new complex function: Making blood
Hat tip: Pos-Darwinista