偉大な分裂:Ardipithecus ramidusは,アフリカの類人猿との最後の共通の祖先の頭蓋骨を明らかにしています
C Owen Lovejoy1, Gen Suwa, Scott W Simpson
1Department of Anthropology, School of Biomedical Sciences, Kent State University, Kent, OH 44242-0001, USA. olovejoy@aol.com
Science (New York, N.Y.)
|October 8, 2009
まとめ
化石の証拠によると,チンパンジーやボノボとの最後の共通の祖先は,猿のような特殊な適応が欠けていたという. 現代のアフリカ類人猿は,この祖先から受け継がれたのではなく,独立して足首の歩き方のような特性を進化させた.
科学分野:
- 古人類学は,古人類学である.
- 進化生物学の進化生物学について
- プリマトロジーは,霊長類学です.
背景:
- ゲノムデータは,チンパンジーとボノボをヒトの最も近い親類として識別しています.
- 遺伝子調節の複雑さは,祖先の解剖学を推論するために現存する類人猿を使用することを制限します.
- 化石記録は歴史的に,初期のホミノイド祖先に関する限られたデータを提供してきました.
研究 の 目的:
- ホミニドと現存するアフリカ類人猿が共有した最後の共通の祖先の解剖学的構造を再構築する.
- アフリカの類人猿とヒト類における特殊な運動適応の進化的起源を調査する.
主な方法:
- 化石記録の分析,特に関連するホミノイド化石に焦点を当てた.
- 化石証拠の比較解剖学的評価と,現存する類人猿の専門化との比較.
- Ardipithecus ramidusのような重要な化石で派生した専門性の欠如に基づく祖先の特徴の推論.
主要な成果:
- Ardipithecus ramidusの化石証拠は,最後の共通の祖先には,吊り下げ,垂直クライミング,足首歩行のための特殊な手,足,骨盤,脊椎,四肢構造が欠けていたことを示しています.
- 現存するアフリカ類人猿の特異性 (サスペンション,垂直クライミング,足首歩行) は,それぞれ独立して進化したようです.
- 先進的な正体調 (直立した姿勢) は,アフリカの類人猿とヒト類に並行して進化した.
- ホミノイド脊髄の変異は,肩帯を横向きに方向転換させ,腰椎を大幅に縮小させなかった.
結論:
- 最後の共通の祖先は,概して樹木に登り,橋渡しをする能力を有していた.
- 現代のチンパンジーやゴリラに特化した運動器の解剖は,祖先の状態を代表するものではありません.
- これらの発見は,人間の二足の起源を理解するためのモデルとして,現存するアフリカの類人猿の使用に挑戦しています.
関連する概念動画
02:31Synteny and Evolution
John H. Renwick first coined the term “synteny” in 1971, which refers to the genes present on the same chromosomes, even if they are not genetically linked. The species with common ancestry tend to show conserved syntenic regions. Therefore, the concept of synteny is nowadays used to describe the evolutionary relationship between species.
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
01:14Cranial Bones: Superior and Posterior View
The superior view of the cranium shows the frontal and paired parietal bones.
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
01:23Phylogeny
Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon (singular). Taxa (plural) can span different levels of the evolutionary hierarchy. For instance, the group containing all birds is a taxon (comprising the class Aves), and the group of all species of daisies (the genus Bellis) is a taxon. Phylogenies can likewise include just one genus (i.e., depict species relationships) or span an entire...
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
01:22Sutures of the Skull
The human skull is composed of several bones that come together to protect the brain and support the structures of the face. The junctions where these bones meet are called sutures.
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...
01:08Overview of the Skull
The cranium (skull) is the skeletal structure of the head that supports the face and protects the brain. It is subdivided into the facial bones and the brain case, or cranial vault. The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws.
The cranial vault surrounds and protects the brain and houses the middle and inner ear structures. This cavity is bounded superiorly by the rounded top of the skull, which...
The cranial vault surrounds and protects the brain and houses the middle and inner ear structures. This cavity is bounded superiorly by the rounded top of the skull, which...