Again, the age of the specimen is unknown and so far I am not aware of other specimens of this type. The variation on a theme may be the “M” type of skull which is even more bizarre than all the previous skulls.
The “M” type of skull is incomplete, as the lower part of the facial area is concerned. What is apparent from the remnants of the facial portion is that the characteristics are entirely within the range of a normal human skull.
The cranial vault, on the other hand, is the largest amongst the displayed specimens. Also, the two protruding “lobes” are highly anomalous.
The cranial capacity can be estimated safely above 3000 cm3 mark.
Both “J” and “M” types are bordering on biological impossibility.
The only explanation I can imagine for the specimens to be naturally born is if the neoteny (the ability of the species to prolong the growth period before maturing) of both groups had been expanded beyond the range for a modern type of human, for the skull to grow to such a size.
That may also mean the average life span of these specimens may have been substantially longer than the average for the modern human type.
Any conjectures that what these specimens represent are simply deformations or pathological cases can be hardly substantiated. Anomalous types of growth or shapes appear from time to time in the modern human population, however, these occurrences are still within the range of the given species.
The largest skull documented in the medical literature had the cranial capacity of 1980 cm3, however, the shape of the skull was normal.
Also, it is necessary to keep in mind that any pathological growth of the cranium has dire consequences for the afflicted individual at the early stage of the development, practically without exception. Nature is very unforgiving in this respect. All the specimens presented here were mature individuals.
The capacity of the cranial vault (and thus the brain mass) and intelligence is not necessarily indicated by the other.
The individual with the largest skull, already mentioned above, was a retarded man, while Anatole France with his 1100 cm3 was quite a brilliant writer.