Miocene Apes and Human Origins 141the face of the Toumai specimen, indicating its status as a
member of the human evolutionary line. Whether or not
this specimen proves to be a direct human ancestor, as the
only skull from this time period it is nevertheless a very
important find.
In 2001, 6-million-year-old fossils discovered in Kenya
by French and British researchers Brigitte Senut and
Martin Pickford were also reported as human ancestors.^18
Officially given the species name Orrorin tugenensis
(Orrorin meaning “original man” and tugenensis meaning
“from the Tugen Hills”) but nicknamed “Millennium
Man,” these specimens have also been surrounded by
controversy.
The evidence for Orrorin consists of fragmentary arm
and thigh bones, a finger bone, some jaw fragments, and
teeth of at least five individuals. The thigh bones demon-
strate possible but not definite bipedalism. Unfortunately,
the distal or far ends of the thigh bone that would prove
this are not fully preserved. The humerus (upper arm) ap-
pears to be more like that of humans than it is like the later
bipedal species we will explore in the next chapter. Also
Orrorin appears to be larger in size than some of these
later bipeds. The methods that paleoanthropologists use
to determine bipedalism from the fossil record will be
fully described in Chapter 7.have the potential to be the missing link between humans
and the other African ape species, the evidence from this
period has been, until recently, particularly scrappy. Con-
troversy surrounds the interpretation of many of these new
fossil finds.
For example, in Chad in the summer of 2002, a team of
international researchers led by Michel Brunet of France
unearthed a well-preserved skull dated to between 6 and
7 mya.^17 Calling their find Sahelanthropus tchadensis
(“Sahel man of Chad,” referring to the Sahel—a belt of
semi-arid land bordering the southern edge of the Sahara
Desert)—the researchers suggested that this specimen
represented the earliest known ancestor of humans, or
earliest biped. Nicknamed “Toumai,” from the region’s
Goran-language word meaning “hope for life” (a name
typically given to babies born just before the dry season),
this specimen is the only skull from this time period.
Considering that bipedalism is the derived charac-
teristic that indicates inclusion in the human subfamily,
some paleoanthropologists argue that the relationship
of this specimen to humans cannot be established from
skull bones alone. The research team argues that derived
features, such as a reduced canine tooth, can be seen in(^18) Senut, B., et al. (2001). First hominid from the Miocene (Lukeino Forma-
tion, Kenya). Comptes Rendus de l’Académie de Sciences 332, 137–144.
© Orbin, Thierry/Corbis Sygma
These 6-million-year-old fossils, discovered in Kenya in 2001, rep-
resent a new species, Orrorin tugenensis, which has also been pro-
posed as the earliest human ancestor. Like Toumai, these bones are
surrounded by controversy. The thigh bones (femora) strongly suggest
bipedalism, and the upper arm bone (humerus) may be more like
that of humans than it is like some of the later bipeds. More discov-
eries and scientific comparisons will solve controversies surrounding
both Orrorin and Toumai.
T r p s b t e b
The spectacular skull from Chad nicknamed “Toumai” (“hope for
life”) has been proposed as the earliest direct human ancestor.
While the 6- to 7-million-year-old specimen is beautifully preserved
and has some derived features, some paleoanthropologists feel that
alone, it does not establish bipedalism, the derived trait characteris-
tic of the human line.
© Michael Brunet
(^17) Brunet, M., et al. (2002). A new hominid from the Upper Miocene of
Chad, Central Africa. Nature 418, 145–151.