Homo (genus)
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Homo sapiens sapiens |
Homo is the primate genus that includes modern humans and their close extinct relatives, such as Homo habilis and Homo erectus—that is, those more closely related to humans than the other great apes (chimpanzees, gorillas, and orangutans).
The word homo is Latin for "person," chosen originally by Carolus Linnaeus in his classification system. It is often translated as "man," although this can lead to confusion, given that the English word "man" can be generic like human or person, but can also specifically refer to males. Latin for "man" in the gender-specific sense is vir, cognate with "virile" and "werewolf". The word "human" is from Latin humanus, an adjective cognate to homo.
Overall classification
Primate taxonomy has undergone a number of revisions in recent years. For some time, Homo sapiens were the only extant species in the family Hominidae, when the great apes chimpanzee, gorilla, and orangutan were placed in a separate family Pongidae (Simpson 1945). Thus, human beings and their extinct relatives were separate from the other apes at the family level. Today, however, it is common to place these great apes and humans and their extinct relatives together in Hominidae. (There are other taxonomic schemes, such as placing extant and extinct chimpanzees and gorillas in the family Panidae, orangutans in the historical group Pongidae, and humans alone in Hominidae.)
Based on the scheme currently popular, the chimpanzees, gorillas, and humans are together in the subfamily Homininae, and chimpanzees and humans are together in the tribe Hominini. Furthermore, humans their extinct relatives (eg. Australopithecines, Neanderthals)—in other words, those closer to humans than to the other great apes—were placed together in the subtribe Hominina.
By various methods (protein differences, DNA differences, etc.), it is determined that the branching point between humans and chimpanzees is more recent than between chimpanzees and gorillas, and thus suggesting that chimpanzees are our nearest relatives (Mayr 2001)). Thus, the gorillas are separated into tribe Gorillini, while extant and extinct humans and chimpanzees are placed in tribe Hominini.
Subsequently, it was decided that the African apes (chimpanzees and gorillas) were more closely related to each other than any of them are related to the organgutans, and the chimpanzees and gorillas were moved into the subfamily Homininae with humans, with orangutans remaining in the subfamily Pongidae. Chimpanzees and humans were further separated into the same tribe, Hominini. Humans and their extinct relatives were further separated into the sub-tribe Hominina.
Thus, orangutans are separated into the subfamily Ponginae while the other great apes are placed in subfamily Homininae. By various methods (protein differences, DNA differences, etc.), it is determined that the branching point between humans and chimpanzees is more recent than between chimpanzees and gorillas, and thus suggesting that chimpanzees are our nearest relatives (Mayr 2001)). Thus, the gorillas are separated into tribe Gorillini, while extant and extinct humans and chimpanzees are placed in tribe Hominini.
The anatomical and biochemical similarity between chimpanzees and humans is indeed striking. Various studies show that they have about 98 to 99.4 percent of their DNA in common (Wildman et al. 2003, Wood 2006). For example, comparisons between chimpanzees and humans in terms of protein sequences, allele differences, and DNA heteroduplex melting points show more than 98 percent identity (King and Wilson 1975; Wood 2006). Ebersberger et al. (2002) found a difference of only 1.24 percent when he aligned 1.9 million nucleotides of chimpanzee DNA and compared them with the corresponding human sequences in the human genome (Wood 2006). Using a 4.97 million nucleotide portion of DNA from human chromosome 7 and comparing to chimpanzee orthologies yielded only 1.13 percent mismatches (Liu et al. 2003). Other biochemical comparisons can be seen in the article on chimpanzees.
In the 1996 proposal of Mann and Weiss, the tribe Hominini includes Pan as well as Homo as separate subtribes. Homo, and, by inference, all bipedal apes, is by itself only in the subtribe Hominina, while Pan is in the Panina subtribe.
Chimpanzees are so similar to humans that some scientists have proposed that the two chimpanzee species, troglodytes and paniscus, belong with sapiens in the genus Homo, rather than in Pan. Of course, this again considers only anatomical and genetic differences, rather than a comprehensive view that includes social, psychological, religious, and other factors.
Members of the genus Homo
The genus is estimated to be between 1.5 and 2.5 million years old. All species except Homo sapiens (modern humans) are extinct. Homo neanderthalensis, traditionally considered the last surviving relative, died out 30,000 years ago while recent evidence suggests that Homo floresiensis lived as recently as 12,000 years ago.
Note:In modern taxonomy, Homo sapiens is the only extant (living) species of its genus, Homo. However, the ongoing study of the origins of Homo sapiens often demonstrates that there were other Homo species, all of which are now extinct. While some of these other species might have been ancestors of H. sapiens, many were likely our "cousins," having speciated away from our ancestral line. There is not yet a consensus as to which of these groups should count as separate species and which as subspecies of another species. In some cases, this is due to the paucity of fossils; in other cases, it is due to the slight differences used to classify species in the Homo genus.
A minority of zoologists consider that the two species of chimpanzees (usually treated in the genus Pan), and maybe the gorillas (usually treated in the genus Gorilla) should also be included in the genus based on genetic similarities. Most scientists argue that chimpanzees and gorillas have too many anatomical differences between themselves and humans to be part of Homo. The genus Homo is most closely related to Kenyanthropus platyops, which is likely to be an ancestral species. Through that species, Homo is next most closely related to the group of extinct species in the genera Paranthropus and Australopithecus, whose evolutionary branch split off from the proto-Homo line some 5 million years ago.
Species
- †Homo habilis (Handy Man)
- †Homo rudolfensis (Rudolf Man)
- †Homo ergaster (Working Man)
- †Homo erectus (Upright Man)
- †Homo floresiensis (Flores Man — discovered 2003)
- †Homo antecessor (Predecessor Man)
- †Homo heidelbergensis (Heidelberg Man)
- †Homo neanderthalensis (Neanderthal Man)
- †Homo rhodesiensis (Rhodesia Man)
- †Homo cepranensis (Ceprano Man)
- †Homo georgicus (Georgia Man)
- Homo sapiens
- †Homo sapiens idaltu (elderly wise man — discovered 1997)
- Homo sapiens sapiens (Wise Man; modern humans)
H. heidelbergensis and H. neanderthalensis are closely related to each other and have been considered to be subspecies of H. sapiens, but analysis of mitochondrial DNA from Homo neanderthalensis fossils shows that H. neanderthalensis is more closely related to chimpanzees than H. sapiens is, thereby suggesting that H. sapiens is the more derived of the two.[1] H. rhodesiensis and H. cepranensis are also more closely related to each other than to the other species.
Template:Homo
ReferencesISBN links support NWE through referral fees
- Serre et al. (2004). No evidence of Neandertal mtDNA contribution to early modern humans. PLoS Biology 2 (3): 313–7. PMID 15024415.
External links
- Hominid species
- For more details, including photos of fossil hominids + modern apes' skulls
- Mikko's Phylogeny archive
Sahelanthropus tchadensis • Orrorin tugenensis • Ardipithecus
Australopithecus: A. anamensis • A. afarensis • A. bahrelghazali • A. africanus • A. garhi
Paranthropus: P. aethiopicus • P. boisei • P. robustus
Kenyanthropus platyops
Homo: H. habilis • H. rudolfensis • H. georgicus • H. ergaster • H. erectus (H. e. lantianensis • H. e. palaeojavanicus • H. e. pekinensis • H. e. soloensis) • H. cepranensis • H. antecessor • H. heidelbergensis • H. neanderthalensis • H. rhodesiensis • H. floresiensis • Homo sapiens (H. s. idaltu • H. s. sapiens)
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