0.12 ⋅ bodyweight 0.66 } \cdot \operatorname ^ brain volume is prominent in the scientific literature for discussing taxonomic identification, behavioral complexity, intelligence, and dissimilar rates of evolution. in modern humans, cranial capacity can vary by as much as 1000 cc, without any correlation to behavior. this degree of variation is almost equivalent to the total increase in volume from australopithecine fossils to modern humans, and brings into question the validity of relying on cranial capacity as a measurement of sophistication. many paleoneurobiologists measure cranial capacity via the submersion method, in which displacement of water in a beaker is taken as the volume of the endocast. scientists who believe that this method is not accurate enough will use a similar procedure in which a beaker with a spout is filled until it is full. the water displaced by the endocast is then weighed to determine the endocast volume. although both of these techniques are significantly more precise than previous methods, scientists are optimistic that more advanced techniques such as computed tomography will provide greater accuracy of volume measurements. morphometric analysis morphometric analysis relies on chord and arc measurements of the endocast surface. length, width, bregma-basion, and height measurements of an endocast are taken with spreading calipers. frontal lobe, parietal lobe, and occipital lobe chord length (the length of the lobe at its widest point along the midsagittal plane) are measured using a dioptograph in which landmarks are projected onto a two-dimensional surface. measurements may be skewed if the orientation of the endocast has not been properly determined before the dioptograph is made. geometric morphometrics (systems of coordinates superimposed over the measurements of the endocast) are often applied to allow comparison between specimens of varying size. measurements may also be taken in reference to broca's area, height of the endocast at 25% intervals of the maximum length, and the vault module (mean of maximum length, width, and middle height). although other measurements may be taken, the choice of landmarks are not always consistent between studies. convolution pattern and cerebral organization convolutions, the individual gyri and sulci that compose the folds of the brain, are the most difficult aspect of an endocast to accurately assess. the surface of the brain is often referred to as smooth and fuzzy, due to the meninges and vasculature that cover the brain's surface. it is possible to observe underlying gyri and sulci patterns if an endocast is accurately or preserved, but the uncertainty associated with these patterns often leads to controversy. because the robust australopithecine fossils show these details, convolutions are included in the study of endocasts whenever appropriate. asymmetry the degree of asymmetry between right and left hemispheres is a point of interest to most paleoneurobiologists because it could be linked to handedness or language development of the specimen. asymmetries occur due to hemispherical specialization and are observed in both a qualitative and quantitative manner. the unevenness of the hemispheres, known as a petalia, is characterized by a lobe that is wider and/or protruding beyond the contralateral lobe. for example, a right-handed person typically has larger left occipital lobe and right frontal lobes than the contralateral lobes. petalias also occur due to specialization in the communication centers of the frontal cortex of the brain in modern humans. petalias in the occipital lobe are easier to detect than those in the frontal lobe. certain asymmetries have been documented on homo erectus specimens such as the homo redolfensis specimen from 1.8 million years ago that resemble the same asymmetries from modern humans. some gorillas have shown strong petalias, but they are not found in combination with other petalias as is almost always the case in humans. scientists use the presence of petalias to show sophistication, but they are not a definitive indicator of evolution toward a more human brain. meningeal patterns although the meninges have no link to behavior, they are still studied within the realm of paleoneurobiology due to the high degree of conservation of meningeal patterns within a species which may serve as a way to determine taxonomy and phylogeny. endocranial vasculature because meningeal blood vessels comprise part of the outermost layer of the brain, they often leave vascular grooves in the cranial cavity that are captured in endocasts. endocranial vasculature originates around the foramina in the skull and in a living body would supply blood to the calvaria and dura mater. the vasculature is so well preserved in some fossils that terminal branches of the circulatory system can be observed. analysis of cranial vasculature concentrates on the anterior meningeal system of the frontal region, the middle meningeal system of the parieto-temporal and part of the anterior occipital region, and the cerebellar fossa system of the cerebellar region. in the course of hominid evolution, the middle meningeal system has undergone the most change. although cranial vasculature has been exhaustively studied in the last century, there has been no consensus on an identification scheme for the branches and patterns of the vascular system resulting from little overlap of results between studies. as such, endocranial vasculature is better suited for inferring the amount of blood delivered to different parts of the brain. relative lobe size it is impossible to determine accurate location of the central or precentral sulci from an endocast. still it can provide a rough idea of lobe sizes. significance the study of paleoneurobiology allows researchers to examine the evolutionary nature of human encephalization. traditionally, paleoneurobiologists have focused on determining the volume of the ancient brain and the patterns that emerged among related species. by finding these measurements, researchers have been able to predict the average body weight of species. endocasts also reveal traits of the ancient brain including relative lobe size, blood supply, and other general insight into the anatomy of evolving species. limitations while paleoneurology is useful in the study of brain evolution, certain limitations to the information this study provides do exist. the limited scale and completeness of the fossil record inhibits the ability of paleoneurobiology to accurately document the course of brain evolution. further, fossil preservation is necessary to ensure accuracy of the endocasts studied. weathering, erosion, and overall gradual disfiguration may alter the naturally recovered endocasts or endocasts created from existing fossils. the morphology of the brain can also be difficult to both quantify and describe, further complicating the observations made from the study of endocasts. additionally, paleoneurobiology provides very little insight into the actual anatomy within the brains of species studied; the study of endocasts is limited to the external anatomy only. the relationship among endocranial traits remains elusive. comparative paleoeneurology reveals mostly only differences in endocranial size among related species, such as gorilla gorilla. since there is no proven direct relationship between brain size and intelligence, only inferences can be made regarding the developing behavior of ancient relatives of the genus homo. these limitations of paleoneurobiology are currently being dealt with by the development of more advanced tools to refine the study of endocasts. studies of interest brain shape, intelligence, and cognitive performance recent studies by emiliano bruner, manuel martin-loechesb, miguel burgaletac, and roberto colomc have investigated the connection between midsagittal brain shape and mental speed. this study incorporated human subjects' cognitive testing in relationship to extinct humans. they used 2d from 102 mri-scanned young adult human for comparison. such correlations are small, suggesting that the influence of midsagittal brain geometry on individual cognitive performance is negligible but still provides useful information of evolutionary traits of the brain. areas associated with the parietal cortex appear to be involved in relationships between brain geometry and mental speed. degenerative diseases and functional disorder scientist j. ghika believes use of paleoneurobiology is the best way to analyze several neurodegeneration leading to diseases such as parkinson's disease, dyskinesias, gait disorders, paget's disease of bone, dysautonomia and so on. a past study by s.i. rapoport on alzheimer's disease in homo sapiens has shown the importance in using a darwinian perspective to better understand this disease itself and its symptoms. the aim is to determine the genetic mechanisms that lead to focal or asymmetrical brain atrophy resulting in syndromic presentations that affect gait, hand movements (any sort of locomotion), language, cognition, mood and behavior disorders.