People took a long time to figure out that evolution happened, and for many years, Western civilization relied largely on the Bible to understand how we got here.
But about the same time that Anglo-Irish Archbishop James Ussher calculated his Earth-formation date of October 26, 4004 BC, some of his keenest contemporaries puzzled over just how the Bible could be literally true.
Early on, the story that caused perhaps the most trouble was Noah's Flood.
One man who managed to stir some doubt was Niels Stensen (or Nicolaus Steno).
The same mount was also analyzed by Geological Survey of Canada (GSC) researchers using the GSC SHRIMP II ion microprobe (Stern and Amelin, 2003).
In our comparison, we determined that variations in U and Pb instrumental fractionation, sputter yield, detection efficiency (useful yield) and analytical reproducibility are very similar for both, the UCLA and GSC instruments, despite prominent differences in design and analytical conditions.
Hairdos differed, but the basic body plan stayed the same for as far back as the history books go. They would be much better at climbing trees, though.
Really far back in time, there wouldn't be any legs at all, just fins for swimming.
Schmitz MD, Bowring SA, and Ireland T (2003)Evaluation of Duluth Complex anorthositic series (AS3) zircon as a U-Pb geochronological standard: New high-precision isotope dilution thermal ionization mass spectrometry results. (2003) Assessment of errors in SIMS zircon U-Pb geochronology using a natural zircon standard and NIST SRM 610 glass.
Biological evolution is change in the characteristics of living organisms over generations.
Interelement fractionation between U, Th and Pb during ion microprobe analysis is monitored using well-characterized standards of known isotopic composition (e.g., AS3, 91500).
Resulting age uncertainties critically depend on how well this fractionation can be monitored.