Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
  High-Bandwidth Version
Search Evolution  
 
Click to return to the Evolution Home Page
darwin change extinction survival sex humans religion
Darwin    
   
Origins of Humankind
border
The Hominid Family Tree

Orrorin tugenensis
(6 mya)

Ardipithecus ramidus
(4.4 mya)

Australopithecus anamensis
(4.2 to 3.9 mya)

Australopithecus afarensis
(3.6 to 2.9 mya)

Kenyanthropus platyops
(3.5 to 3.3 mya)

Australopithecus africanus
(3 to 2 mya)

Australopithecus aethiopicus
(2.7 to 2.3 mya)

Australopithecus garhi
(2.5 mya)

Australopithecus boisei
(2.3 to 1.4 mya)

Homo habilis
(2.3 to 1.6 mya)

Homo erectus
(1.8 to 0.3 mya)

Australopithecus robustus
(1.8 to 1.5 mya)

Homo heidelbergensis
(600 to 100 tya)

Homo neanderthalensis
(250 to 30 tya)

Homo sapiens
(100 tya to present)

mya = millions of years ago        tya = thousands of years ago

border

Ardipithecus ramidus (4.4 million years ago)*

*Because fossil evidence for Ardipithecus ramidus is scant, a range of dates for when this species lived is not available.

Species Description:

Ardipithecus ramidus was discovered in December 1992. Although not nearly as old as Orrorin tugenensis, Ar. ramidus is much more widely accepted by the scientific community as a hominid than is O. tugenensis, and thus is considered by some to be the oldest-known hominid.

A partial skeleton and indirect evidence from skeletal fragments indicate that Ar. ramidus may have walked upright. Although considered to be one of the most primitive hominids, Ar. ramidus shares some novel characteristics with much later hominids, namely aspects of its teeth. The molars of Ar. ramidus are smaller than are those of any of the Australopithecus species.

Other fossils found with Ar. ramidus suggest that it may have been a woodland forest dweller. This may modify current theories about why hominids became bipedal in the first place. Walking upright has typically been linked to movement onto the savanna.

(Note: This species has not yet been fully described because some of the specimens have been difficult to extract from the surrounding rock.)

Fossil Finds:

ARA-VP-1/129
Estimated age: 4.4 million years
Date of discovery: 1992, 1993
Location: Aramis, Ethiopia

A partial lower jaw from a child is one of several fossils known for this species. This partial jaw, catalogued as ARA-VP-1/129, shows very primitive tooth structure relative to later hominid species. Other fossils -- including teeth, an adult mandible, pieces of a skull, and several arm bones -- show an interesting mix of primitive and advanced characteristics.

-> Go to Australopithecus anamensis

 
  related web activities  
   
Riddle of the Bones
Piece together clues about our early ancestors.
 
 
Deep Time
Explore 4 billion years of life on Earth.
 
 
Life's Grand Design
Are nature's complex forms evidence of "intelligent design?"
 
   
An Origin of Species
Witness for yourself how a new species can evolve.
 
 
  related topics  
   
  Human Evolution  
   
  Adaptation and Natural Selection  
   
  Deep Time/History of Life  
 
 
       
         
 
Videos Web Activities Site Guide About the Project FAQ Glossary Site Map Feedback Help Shop