Evolution What the Fossils Say and Why it Matters

146 Evolution and the Fossil Record

biochemical systems (starting with the simple immunological distance method) and always
concluded that the divergence point between apes and humans was 5–7 million years ago.
During the 1970s and early 1980s, there were many bitter debates over the point, so that
Sarich was even quoted as saying that a fossil older than 8 million years old cannot be a
hominid, no matter what it looks like! But in the late 1980s, additional, more complete fossils
were found in Pakistan that showed that Ramapithecus was more like an orangutan and was
actually a member of the genus Sivapithecus. In this case, the molecular biologists were right,
and the paleontologists who staked their careers on Ramapithecus had to lick their wounds.
Likewise, Vincent Sarich was one of the first (based on molecular evidence) to say that
whales were descended from even-toed hoofed mammals (the Artiodactyla) and particularly
closely related to the hippopotamus. That radical idea was backed up by many more molecu-
lar studies and was finally corroborated in 2001 when two different groups of paleontologists
(Gingerich et al. 2001; Thewissen et al. 2001) found the ankle bones of two different kinds
of primitive whales from Pakistan that showed their relationships to the artiodactyls (see

FIGURE 5.6. The fundamental tree of life derived from molecular data, showing the major kingdoms of pro-
karyotes (Eubacteria, Archaebacteria, and many other microbes), and the small side branch of eukaryotes
(plants, animals, and fungi).

Purple bacteria

Cyanobacteria

Gram-positive bacteria

Flavobacteria

Green nonsulfur bacteria

Thermotogales

Halophilic archaeans

Methanosarcina

Methanobacterium

Methanococcus

T. celer

Thermoproteus

Pyrodictium

Diplomonads

Microsporidia

Trichomonads

Flagellates

Entamoebae

Slime molds

Ciliates

Fungi

Plants

Animals