होमो हैबिलिस जीवाश्म होमिनिन

होमो हैबिलिस, (लैटिन: "सक्षम आदमी" या "आसान आदमी") मानव की विलुप्त प्रजाति, मानव जीनस का सबसे प्राचीन प्रतिनिधि, होमो। होमो हैबिलिस ने उप-सहारा अफ्रीका के कुछ हिस्सों में लगभग 2.4 से 1.5 मिलियन साल पहले (मैया) निवास किया। 1959 और 1960 में उत्तरी तंजानिया के ओल्डुवई गॉर्ज में पहला जीवाश्म खोजा गया था। यह खोज जीवाश्म विज्ञान में एक महत्वपूर्ण मोड़ थी क्योंकि सबसे पुराने ज्ञात मानव जीवाश्म होमो इरेक्टस के एशियाई नमूने थे। एच। हैबिलिस की कई विशेषताएं अपेक्षाकृत आदिम आस्ट्रेलोपिथेकस और अधिक-उन्नत होमो प्रजाति के बीच विकासवादी विकास के संदर्भ में मध्यवर्ती हैं।

ओल्डुवई में पाए गए पहले पुष्ट अवशेष में कई दांत और एक निचला जबड़ा एक कपाल और कुछ हाथ की हड्डियों के टुकड़ों से जुड़ा हुआ है। जैसा कि उत्तरी केन्या में कोबी फोरा जैसे स्थानों पर अधिक नमूनों का पता लगाया गया था, शोधकर्ताओं ने महसूस करना शुरू कर दिया कि ये होमिनिन ऑस्ट्रेलियाई-ऑप्थोपिथेकस से शारीरिक रूप से भिन्न थे, जो अधिक एपेलिक जीवों की एक जीनस थे जो कई अफ्रीकी साइटों पर पाए गए हैं। खोजों की औपचारिक घोषणा 1964 में मानवविज्ञानी लुइस एसबी लीके, फिलिप टोबियास और जॉन नेपियर द्वारा की गई थी। ऑस्ट्रोपोपिथेकस के बजाय अपने नए प्राणी होमो को नामित करने के औचित्य के रूप में, उन्होंने बढ़ती कपाल क्षमता और जीवाश्मों के तुलनात्मक रूप से छोटे दाढ़ और प्रीमोलर दांतों का वर्णन किया, एक मानवीय पैर,और हाथ की हड्डियाँ जो सटीकता के साथ वस्तुओं में हेरफेर करने की क्षमता का सुझाव देती हैं - इसलिए प्रजाति का नाम होमो हैबिलिस, या "आसान आदमी" है। इसके अलावा, जीवाश्मों के साथ सरल पत्थर के उपकरण पाए गए। इन सभी विशेषताओं ने एच। एक्टेकस और बाद के मनुष्यों के शरीर रचना विज्ञान और व्यवहार को आगे बढ़ाया, जिससे एच। हैबिलिस को बेहद महत्वपूर्ण बना दिया, भले ही इसके कुछ अवशेष हैं।

जीवाश्म साक्ष्य

ओल्डुवाई होमिनिड 7 (ओएच 7) नामक एक किशोर व्यक्ति से कपाल और हाथ की हड्डियों की 1.8 मिलियन वर्ष पुरानी खोज के अलावा, ओल्डूई से अतिरिक्त जीवाश्मों को एच। हेबिलिस में भेजा गया है। 1963 में ऊपरी और निचले जबड़े और दांतों के साथ एक और पतली दीवार वाले कपाल के टुकड़े प्रकाश में आए। एक महीने बाद तीसरी खोपड़ी मिली, लेकिन हड्डियों को मवेशियों द्वारा गल जाने के बाद रौंद दिया गया। कुछ दाँत बच गए, लेकिन कपाल कई छोटे टुकड़ों में टूट गया; केवल ब्रेनकेस के शीर्ष, या तिजोरी, वापस एक साथ pieced किया गया है। उन दो खोपड़ियों को OH 13 और OH 16 कहा जाता है।

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Since 1964 more material has been discovered. One intriguing specimen is OH 24, which was also from Olduvai and dated to about 1.8 mya. This cranium is more complete than others from Olduvai. Because some of the bones are crushed and distorted, however, the face and braincase are warped. OH 24 may differ from Australopithecus in brain size and dental characteristics, but it resembles the australopiths of southern Africa in other features, such as the shape of the face.

Important discoveries made in the Koobi Fora region of northern Kenya include a controversial skull called KNM-ER 1470 (Kenya National Museum–East Rudolf), which was discovered in 1972 and dated to 1.9 mya. The specimen resembles both Australopithecus and Homo. As in the case of OH 16, this specimen had been broken into many fragments, which could be collected only after extensive sieving of the deposits. Some of the pieces were then fitted into the reconstruction of a face and much of a large vault. Brain volume can be measured rather accurately and is about 750 cubic cm (cc), or 46 cubic inches. This evidence prompted some paleoanthropologists to describe ER 1470 as one of the most ancient undoubted representatives of the genus Homo because some other features of the braincase are also Homo-like. At the same time, it is apparent that the facial skeleton is relatively large and flattened in its lower parts. In this respect, the Koobi Fora specimen resembles Australopithecus anatomically.

Among other key finds from the Koobi Fora region are KNM-ER 1813 and KNM-ER 1805. Both were discovered in 1973, with ER 1813 dated to 1.9 mya and ER 1805 dated to 1.7 mya. The former, which is most of a cranium, is smaller than ER 1470 and resembles OH 13 in many details, including tooth size and morphology. The latter skull exhibits some peculiar features. Although the braincase of ER 1805 is close to 600 cc (36.6 cubic inches) in volume and is thus expanded moderately beyond the size expected in Australopithecus, a bony crest runs along the top of the skull. This sagittal crest is coupled with another prominent crest oriented across the rear of the skull. These ridges indicate that the chewing muscles and neck muscles were powerfully developed. A similar if more-exaggerated pattern of cresting appears in the so-called robust australopiths but not in Homo. Other features of ER 1805, however, are Homo-like. As a result, there has been disagreement among anatomists regarding the hominin species to which this individual should be assigned. Despite its anomalies, ER 1805 is often discussed along with other specimens grouped as H. habilis.

Several mandibles resembling that of OH 7 have been recovered from the Koobi Fora area, and teeth that may belong to H. habilis have been found farther to the north, in the Omo River valley of Ethiopia. Some additional material, including a badly broken cranium, are known from the cave at Swartkrans in South Africa. At Swartkrans the fossils are mixed with many other bones of robust australopiths. An early species of Homo may also be present at Sterkfontein, not far from Swartkrans. Here again the remains are fragmentary and not particularly informative.

A more-valuable discovery was reported from Olduvai Gorge in 1986. A jaw with teeth and skull fragments as well as pieces of a right arm and both legs were found. The bones seem to represent one individual, dated to 1.8 mya and called OH 62. Although the skull is shattered, enough of the face is preserved to suggest similarities to early Homo. The find is especially important because of the limbs, which show that OH 62 was a very small hominin. The arm is long relative to the leg, resulting in body proportions that differ dramatically from those of more-modern hominins.

One of the more-important 21st-century discoveries included a mandible found at the Ledi-Geraru research site in Ethiopia’s Awash River valley in 2013, which could be the oldest known specimen attributed to H. habilis. Dated to 2.8–2.75 mya, it possesses some of the primitive traits that occur in Australopithecus while also containing derived features (such as smaller teeth and a much-reduced chin) associated with later species of Homo. The specimen has proved useful for bridging the nearly one-million-year gap in dating between fossils associated with A. afarensis and fossils associated with Homo. However, many paleontologists—including the discoverer, American paleontologist Brian Villmoare—are hesitant to associate it unequivocally with H. habilis until additional remains are found.