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55-397: Although this usage was common in the sciences for much of the 20th century, it is now considered rare. More generally, the term can refer to anything with distinctly human characteristics or adaptations, such as possessing opposable anterior forelimb - appendages (i.e. thumbs), visible spectrum - binocular vision (i.e. having two eyes), or biomechanic plantigrade - bipedalism (i.e.

110-415: A humanoid of dinosaur origin. Over geologic time, Russell noted that there had been a steady increase in the encephalization quotient or EQ (the relative brain weight when compared to other species with the same body weight) among the dinosaurs. Russell had discovered the first Troodontid skull, and noted that, while its EQ was low compared to humans, it was six times higher than that of other dinosaurs. If

165-473: A flagpole; tension from these muscular guy-wires must be provided in all directions to maintain stability in the articulated column formed by the bones of the thumb. Because this stability is actively maintained by muscles rather than by articular constraints, most muscles attached to the thumb tend to be active during most thumb motions. The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in

220-524: A forerunner of Homo sapiens . This, however, is the suggested result of evolution from Homo erectus (around 1 mya ) via a series of intermediate anthropoid stages, and is therefore a much more complicated link. Modern humans are unique in the musculature of their forearm and hand. Yet, they remain autapomorphic, meaning each muscle is found in one or more non-human primates. The extensor pollicis brevis and flexor pollicis longus allow modern humans to have great manipulative skills and strong flexion in

275-403: A generally humanoid shape is likely, though octopus- or starfish-like bodies are also possible. An opposing view is given by Mike Wall, who argues that intelligent extraterrestrials able to contact Humans would most likely have reached a phase allowing them to develop themselves into machines. Several in-universe explanations have been offered for the abundance of humanoids. One of the more common

330-493: A hierarchy of cooperating systems that make up any organism . Luis Villazon points out that animals that move necessarily have a front and a back; as with animals on Earth , sense organs tend to gather at the front as they encounter stimuli there, forming a head . Legs reduce friction, and with legs, bilateral symmetry makes coordination easier. Sentient organisms will, Villazon argues, likely use tools, in which case they need hands and at least two other limbs to stand on. In short,

385-709: A multitude of worlds toward a humanoid form. In the television series Stargate SG-1 , the Jaffa are explained as being a hundred-thousand year offshoot of humanity bred by the Goa'uld to suit their purposes, hence their almost-human appearance and physiology, while many other "alien" characters are actually the descendants of human- slaves who were removed from Earth by the Goa'uld. Any humans isolated on multiple planets after 100k+ years of adaptations would most certainly seem "alien" to Earthlings. Similarly, in its spin-off show Stargate Atlantis ,

440-408: A navel, as a placenta aids the development of a large brain case. However, it would not have possessed mammary glands and would have fed its young, as birds do, on regurgitated food. He speculated that its language would have sounded somewhat like bird song . Russell's thought experiment has been met with criticism from other paleontologists since the 1980s, many of whom point out that his Dinosauroid

495-519: A real person as possible, although these words are frequently perceived to be synonymous with a humanoid. While there are many humanoid robots in fictional stories, some real humanoid robots have been developed since the 1990s, and some real human-looking android robots have been developed since 2002. Similarly to robots, virtual avatars may also be called humanoid when resembling humans. Deities are often imagined in human shape (also known as " anthropotheism "), sometimes as hybrids (especially

550-483: A result of similar evolutionary pressures. American psychologist and Dinosaur intelligence theorist Harry Jerison suggested the possibility of sapient dinosaurs. In a 1978 presentation at the American Psychological Association , he speculated that dromiceiomimus could have evolved into a highly intelligent species like human beings. In his book, Wonderful Life , Stephen Jay Gould argues if

605-439: A rotary movement is referred to as circumduction . Primatologists and hand research pioneers John and Prudence Napier defined opposition as: "A movement by which the pulp surface of the thumb is placed squarely in contact with – or diametrically opposite to – the terminal pads of one or all of the remaining fingers." For this true , pulp-to-pulp opposition to be possible, the thumb must rotate about its long axis (at

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660-449: A suffixed form of * penkwe (or * penqe ), which has given rise to many Indo-European -family words (tens of them defined in English dictionaries) that involve, or stem from, concepts of fiveness. The thumb shares the following with each of the other four fingers: The thumb contrasts with each of the other four fingers by being the only one that: and hence the etymology of

715-425: A terrestrial lifestyle has led to reduced finger length and thus hand proportions similar to those of humans. Consequently, these primates have dexterous hands and are able to grasp objects using a pad-to-pad grip. It can thus be difficult to identify hand adaptations to manipulation-related tasks based solely on thumb proportions. The evolution of the fully opposable thumb is usually associated with Homo habilis ,

770-622: A trait of primates , crows , and dolphins , at some point. In 1982, Dale Russell , curator of vertebrate fossils at the National Museum of Canada in Ottawa , conjectured a possible evolutionary path that might have been taken by the dinosaur Troodon had it not perished in the Cretaceous–Paleogene extinction event 66 million years ago, suggesting that it could have evolved into intelligent beings similar in body plan to humans, becoming

825-443: Is pollical . The English word finger has two senses , even in the context of appendages of a single typical human hand: 1) Any of the five terminal members of the hand. 2) Any of the four terminal members of the hand, other than the thumb. Linguistically, it appears that the original sense was the first of these two: * penkwe-ros (also rendered as * penqrós ) was, in the inferred Proto-Indo-European language ,

880-547: Is a human characteristic. Darwinius masillae , an Eocene primate transitional fossil between prosimian and simian , had hands and feet with highly flexible digits featuring opposable thumbs and halluces. Additionally, in many polydactyl cats , both the innermost toe and outermost toe ( pinky ) may become opposable, allowing the cat to perform more complex tasks. In addition to these, some other dinosaurs may have had partially or completely opposed toes in order to manipulate food and/or grasp prey. The skeleton of

935-467: Is a robot that is based on the general structure of a human, such as a robot that walks on two legs and has an upper torso, or a robot that has two arms, two legs and a head. A humanoid robot does not necessarily look convincingly like a real person, for example, the ASIMO humanoid robot has a helmet instead of a face. An android (male) or gynoid (female) is a humanoid robot designed to look as much like

990-530: Is overly anthropomorphic. Gregory S. Paul (1988) and Thomas R. Holtz, Jr. , consider it "suspiciously human" (Paul, 1988) and Darren Naish has argued that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan, with a horizontal posture and long tail, and would probably manipulate objects with the snout and feet in the manner of a bird, rather than with human-like "hands". (Although bipedal dinosaurs often do have hands , if they don't turn them into wings.) A humanoid robot

1045-404: Is that authors use the only example of intelligent life that they know, humans. In live-action television and films, using humanoid aliens makes it easier to cast human actors to portray alien characters. A study by the zoologist Sam Levin suggests that aliens might indeed resemble humans, given that they are presumably subject to natural selection . Levin argues that this can be expected to produce

1100-516: Is that the humanoids in the story have evolved on an Earth-like planet or natural satellite , totally independently from Humans on Earth . However, some works have offered alternative explanations: In Star Trek , the explanation is given that a primordial humanoid civilization, the Ancient humanoids , seeded the Milky Way Galaxy with genetically engineered cells to guide the evolution of life on

1155-477: The ankle or foot that allow humans to walk on two legs". Evidence to date shows that of the 110,000 gene enhancer sequences identified in the human genome , HACNS1 has undergone the most change during the human evolution since the chimpanzee–human last common ancestor . Troodontid Too Many Requests If you report this error to the Wikimedia System Administrators, please include

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1210-406: The bi-modality seen in other recessive genetic traits. Other variations of the thumb include brachydactyly type D (which is a thumb with a congenitally short distal phalanx), a triphalangeal thumb (which is a thumb which has 3 phalanges instead of the usual two), and polysyndactyly (which is a combination of radial polydactyly and syndactyly). One of the earlier significant contributors to

1265-414: The carpometacarpal joint ). Arguably, this definition was chosen to underline what is unique to the human thumb. The spider monkey compensates for being virtually thumbless by using the hairless part of its long, prehensile tail for grabbing objects. In apes and Old World monkeys , the thumb can be rotated around its axis, but the extensive area of contact between the pulps of the thumb and index finger

1320-405: The deep branch of the radial nerve (C7-T1). The tendons of the extensor pollicis longus and extensor pollicis brevis form what is known as the anatomical snuff box (an indentation on the lateral aspect of the thumb at its base) The radial artery can be palpated anteriorly at the wrist (not in the snuffbox). There are three thenar muscles : The abductor pollicis brevis (APB) originates on

1375-576: The gods of Ancient Egyptian religion ). A fragment by the Greek poet Xenophanes describes this tendency, ...Men make gods in their own image; those of the Ethiopians are black and narrow-nosed, those of the Thracians have blue eyes and red hair. In animism in general, the spirits innate in certain objects (like the Greek nymphs ) are typically depicted in human shape, e.g. spirits of trees ( Dryads ), of

1430-415: The scaphoid tubercle and the flexor retinaculum . It inserts to the radial sesamoid bone and the proximal phalanx of the thumb. It is innervated by the median nerve (C8-T1). The flexor pollicis brevis (FPB) has two heads. The superficial head arises on the flexor retinaculum, while the deep head originates on three carpal bones: the trapezium , trapezoid , and capitate . The muscle is inserted onto

1485-471: The Black Lagoon , made in 1954 by Jack Arnold . Opposable The thumb is the first digit of the hand , next to the index finger . When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb is pollex (compare hallux for big toe), and the corresponding adjective for thumb

1540-899: The ability to walk on heels and metatarsals in an upright position). Humanoids may also include human-animal hybrids (where each cell has partly human and partly animal genetic contents) and human-animal chimeras (where some cells are human and some cells are animal in origin). Science fiction media frequently present sentient extraterrestrial lifeforms as humanoid as a byproduct of convergent evolution . Humanoid characters are defined by their human-like physical characteristics and forms, which can vary. These characters may appear entirely human, predominantly human-like (e.g., Saiyans from Dragon Ball Z , Martians and Kryptonians from DC Comics ), or they may possess general non-human traits while still having human-like physical characteristics (e.g., human-like Pokémon , ThunderCats characters, various characters from The Amazing World of Gumball ). In

1595-588: The anatomical basis of hand movement. Napier proposed two primary prehensile grips: the precision grip and the power grip . The precision and power grip are defined by the position of the thumb and fingers where: Opposability of the thumb should not be confused with a precision grip as some animals possess semi-opposable thumbs yet are known to have extensive precision grips ( Tufted Capuchins for example). Nevertheless, precision grips are usually only found in higher apes, and only in degrees significantly more restricted than in humans. The pad-to-pad pinch between

1650-441: The base of the distal phalanx of the thumb. It is innervated by the anterior interosseus branch of the median nerve (C7-C8) It is a persistence of one of the former contrahentes muscles that pulled the fingers or toes together. Three dorsal forearm muscles act on the thumb: The abductor pollicis longus (APL) originates on the dorsal sides of both the ulna and the radius, and from the interosseous membrane. Passing through

1705-446: The dorsal side of the ulna and the interosseous membrane. Passing through the third tendon compartment, it is inserted onto the base of the distal phalanx of the thumb. It uses the dorsal tubercle on the lower extremity of the radius as a fulcrum to extend the thumb and also dorsiflexes and abducts the hand at the wrist. It is innervated by the deep branch of the radial nerve (C7-C8). The extensor pollicis brevis (EPB) originates on

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1760-627: The explanation offered for the humanoid appearance of the Wraith is that the Wraith evolved from a parasite which incorporated human DNA into its own genome after feeding on humans, giving the Wraith their present form. In the field of ufology , humanoid refers to any of the claimed extraterrestrials which abduct human victims, such as the Greys , the Reptilians , Nordics , and Martians . In fantasy settings

1815-434: The first and second (proximal and distal) phalanges varies between 0° and almost 90° when the thumb is in a thumbs-up gesture. It has been suggested that the variation is an autosomal recessive trait , called a hitchhiker's thumb , with homozygous carriers having an angle close to 90°. However this theory has been disputed, since the variation in thumb angle is known to fall on a continuum and shows little evidence of

1870-400: The first metacarpal. It opposes the thumb and assists in adduction. It is innervated by the median nerve . Other muscles involved are: The adductor pollicis also has two heads. The transversal head originates along the entire third metacarpal bone, while the oblique head originates on the carpal bones proximal to the third metacarpal. The muscle is inserted onto the ulnar sesamoid bone of

1925-444: The first tendon compartment, it inserts to the base of the first metacarpal bone . A part of the tendon reaches the trapezium, while another fuses with the tendons of the extensor pollicis brevis and the abductor pollicis brevis. Except for abducting the hand, it flexes the hand towards the palm and abducts it radially. It is innervated by the deep branch of the radial nerve (C7-C8). The extensor pollicis longus (EPL) originates on

1980-447: The forearm, and the intrinsic hand muscles, with their muscle bellies located in the hand proper. A ventral forearm muscle, the flexor pollicis longus (FPL) originates on the anterior side of the radius distal to the radial tuberosity and from the interosseous membrane . It passes through the carpal tunnel in a separate tendon sheath , after which it lies between the heads of the flexor pollicis brevis. It finally attaches onto

2035-422: The grasping hand, the distal pads can therefore conform to uneven surfaces while pressure is distributed more evenly in the finger tips. The distal pad of the human thumb is divided into a proximal and a distal compartment, the former more deformable than the latter, which allows the thumb pad to mold around an object. In robotics, almost all robotic hands have a long and strong opposable thumb. Like human hands,

2090-486: The latter case, they often overlap with anthropomorphic characters, with humanoid characters being a subtype of anthropomorphism, specifically in terms of physical characteristics. Although there are no known humanoid species outside the genus Homo , the theory of convergent evolution speculates that different species may evolve similar traits, and in the case of a humanoid these traits may include intelligence and bipedalism and other humanoid skeletal changes , as

2145-410: The metacarpophalangeal joint. It adducts the thumb, and assists in opposition and flexion. It is innervated by the deep branch of the ulnar nerve (C8-T1). The first dorsal interosseous , one of the central muscles of the hand, extends from the base of the thumb metacarpal to the radial side of the proximal phalanx of the index finger. There is a variation of the human thumb where the angle between

2200-446: The motor sequencing of the thumb. A primitive autonomization of the first carpometacarpal joint (CMC) may have occurred in dinosaurs. A real differentiation appeared an estimated 70 mya in early primates, while the shape of the human thumb CMC finally appears about 5 mya. The result of this evolutionary process is a human CMC joint positioned at 80° of pronation, 40 of abduction, and 50° of flexion in relation to an axis passing through

2255-413: The radial sesamoid bone of the metacarpophalangeal joint. It acts to flex, adduct, and abduct the thumb, and is therefore also able to oppose the thumb. The superficial head is innervated by the median nerve , while the deep head is innervated by the ulnar nerve (C8-T1). The opponens pollicis originates on the tubercle of the trapezium and the flexor retinaculum. It is inserted onto the radial side of

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2310-434: The second and third CMC joints. Opposable thumbs are shared by some primates , including most catarrhines . The climbing and suspensory behaviour in orthograde apes, such as chimpanzees , has resulted in elongated hands while the thumb has remained short. As a result, these primates are unable to perform the pad-to-pad grip associated with opposability. However, in pronograde monkeys such as baboons , an adaptation to

2365-412: The study of hand grips was orthopedic primatologist and paleoanthropologist John Napier , who proposed organizing the movements of the hand by their anatomical basis as opposed to work done earlier that had only used arbitrary classification. Most of this early work on hand grips had a pragmatic basis as it was intended to narrowly define compensable injuries to the hand, which required an understanding of

2420-402: The tape of life were re-wound and played back, life would have taken a very different course. Simon Conway Morris counters this argument, arguing that convergence is a dominant force in evolution and that since the same environmental and physical constraints act on all life, there is an "optimum" body plan that life will inevitably evolve toward, with evolution bound to stumble upon intelligence,

2475-588: The term humanoid is used to refer to a human-like fantastical creature, such as a dwarf , elf , gnome , halfling , goblin , troll , orc or an ogre , and Bigfoot . In some cases, such as older versions of the game Dungeons & Dragons , a distinction is made between demi-humans , which are relatively similar to humans, and humanoids, which exhibit larger differences from humans. Animals that are humanoid are also shown in fantasy. Humanoids are also used in some old horror movies, for example in Creature From

2530-417: The thumb and index finger is made possible because of the human ability to passively hyperextend the distal phalanx of the index finger. Most non-human primates have to flex their long fingers in order for the small thumb to reach them. In humans, the distal pads are wider than in other primates because the soft tissues of the finger tip are attached to a horseshoe-shaped edge on the underlying bone, and, in

2585-443: The thumb consists of the first metacarpal bone which articulates proximally with the carpus at the carpometacarpal joint and distally with the proximal phalanx at the metacarpophalangeal joint . This latter bone articulates with the distal phalanx at the interphalangeal joint . Additionally, there are two sesamoid bones at the metacarpophalangeal joint. The muscles of the thumb can be compared to guy-wires supporting

2640-467: The thumb of a robotic hand also plays a key role in gripping an object. One inspiring approach of robotic grip planning is to mimic human thumb placement. In a sense, human thumb placement indicates which surface or part of the object is good for grip. Then the robot places its thumb to the same location and plans the other fingers based on the thumb placement. The function of the thumb declines physiologically with aging. This can be demonstrated by assessing

2695-466: The thumb. However, a more likely scenario may be that the specialized precision gripping hand (equipped with opposable thumb) of Homo habilis preceded walking, with the specialized adaptation of the spine, pelvis, and lower extremities preceding a more advanced hand. And, it is logical that a conservative, highly functional adaptation be followed by a series of more complex ones that complement it. With Homo habilis , an advanced grasping-capable hand

2750-403: The transition between flexion-abduction and extension-adduction; the side of the distal thumb phalanx thus approximated to the palm or the hand's radial side (side of index finger) during apposition and the pulp or "palmar" side of the distal thumb phalanx approximated to either the palm or other fingers during opposition . Moving a limb back to its neutral position is called reposition and

2805-644: The trend in Troodon evolution had continued to the present, its brain case could by now measure 1,100 cm; comparable to that of a human. Troodontids had semi-manipulative fingers, able to grasp and hold objects to a certain degree, and binocular vision. Russell proposed that this " Dinosauroid ", like most dinosaurs of the troodontid family, would have had large eyes and three fingers on each hand, one of which would have been partially opposed . As with most modern reptiles (and birds), he conceived of its genitalia as internal. Russell speculated that it would have required

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2860-399: The ulna distal to the abductor pollicis longus, from the interosseus membrane, and from the dorsal side of the radius. Passing through the first tendon compartment together with the abductor pollicis longus, it is attached to the base of the proximal phalanx of the thumb. It extends the thumb and, because of its close relationship to the long abductor, also abducts the thumb. It is innervated by

2915-405: The woodlands (the hybrid fauns ), of wells or waterways ( Nereids , Necks ), etc. With regard to extraterrestrials in fiction , the term humanoid is most commonly used to refer to alien beings with a body plan that is generally like that of a human, including upright stance and bipedalism , as well as intelligence. In much of science fiction , humanoid aliens are abundant. One explanation

2970-689: The word: * tum is Proto-Indo-European for 'swelling' (cf 'tumor' and 'thigh') since the thumb is the stoutest of the fingers. Anatomists and other researchers focused on human anatomy have hundreds of definitions of opposition . Some anatomists restrict opposition to when the thumb is approximated to the fifth finger (little finger) and refer to other approximations between the thumb and other fingers as apposition . To anatomists, this makes sense as two intrinsic hand muscles are named for this specific movement (the opponens pollicis and opponens digiti minimi respectively). Other researchers use another definition, referring to opposition-apposition as

3025-465: Was accompanied by facultative bipedalism , possibly implying, assuming a co-opted evolutionary relationship exists, that the latter resulted from the former as obligate bipedalism was yet to follow. Walking may have been a by-product of busy hands and not vice versa. HACNS1 (also known as Human Accelerated Region 2) is a gene enhancer "that may have contributed to the evolution of the uniquely opposable human thumb, and possibly also modifications in

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