Counting decapitated sperm and other time-consuming science tasks

Are we done yet?
cheese in a flask on a scale

1 to 2 days. illustration by Rafael Alvarez

scientist pipeting in the lab
Sometimes, science takes forever. Wikimedia Commons

Modern science is fast; the advent of computers, algorithms, and artificial intelligence helps scientists accomplish in seconds what used to take days. Some efforts, though, still require a slower pace or the keen skill of the human eye and brain. For these experiments, time is a crucial ingredient. Here’s a look at a few particularly painstaking duties—and just how long scientists spend on them.

As told to Kaitlin Sullivan


Victor W. Weedn, forensic scientist at George Washington University: Sperm are hard to find under a microscope, so we use a special dye to turn the heads red and tails green. But the tails often break off, leaving the heads, which, unless carefully examined, look like totally different cells. To make sure we find the sperm, we take it slow.

fly eggs

Nilay Yapici, neurobiologist at Cornell University: In an attempt to pinpoint a similar protein found in fruit flies and mosquitoes that could stop skeeters from biting, I genetically modified 400,000 flies and counted, by hand, millions of eggs. This was during graduate school in 2007, but manual tallying is still the quickest method.

tree rings

Ronald H. Towner, archaeological dendrochronologist at the University of Arizona: Tallying and measuring tree-ring widths helps archaeologists date ancient lumber. Computer programs often total the circles, but in dry places such as Arizona, drought years produce faint marks that only the human eye can discern.


Daryll LaCourse, Amateur astronomer, Zooniverse, a citizen science project: I’m one of thousands of hobby scientists NASA commissioned to find exoplanets in data from the ­Kepler Telescope, which imaged more than half a million stars. Tiny variations among plotted points are planets in orbit, which computers can miss. We found about 4,000.

Tonya Schoenfuss, Dairy Products specialist at the University of Minnesota: My lab uses titration (adding one solution, drop by drop, to another until they neutralize) to quantify the protein in cheese. The steps preceding titration are the longest. That includes boiling the cheese for hours in sulfuric acid to dissolve it.

This article was originally published in the Summer 2019 Make It Last issue of Popular Science.