4.5 Tools and the Visual System

The hominin line diverged from the common ancestor of African apes

some 6 mya. As was noted above, the brains of Australopithecines got no

bigger than that of a chimpanzee. Therefore, from research on primates

and monkeys, coupled with the archeological and geological data, we have

an idea of what the brain and visual system of Australopithecines may have

looked like and how they would have performed (Dunbar, 1988; see the

articles in Berthelet & Chavaillon, 1993). The neurophysiology and lifestyle

of Early Australopithecines, like A. anamensis, were probably similar to

those of present-day chimps.

However, the climate in Africa slowly changed. Approximately 8 mya,

present-day India (which was separate from Asia prior to this time) butted

up against Asia and formed the Himalayan mountains, thereby robbing

Africa of excess amounts of water. This climatic change caused eastern

Africa to be transformed from predominantly forested environments, to

savanna-like environments of forest and open range, to open range environments

with little or no forestation (Calvin, 2001, 2004; Potts, 1996;

Eldredge, 2001). Daly & Wilson (1999), Foley (1995), and Boyd & Silk

(1997) have shown that the Pleistocene epoch did not consist of a single

hunter–gatherer type of environment but was actually a constellation of

environments that presented a host of challenges to the early hominin

mind. The climate shift in Africa from jungle life to desert/savanna life

forced our early hominins to come out of the trees and survive in totally

new environments (Tattersall, 2001; Calvin, 2004; Aiello, 1997; Fleagle,

1999).

If the Australopithecines wanted to continue to live a life in the trees, they

would have had to spend more time on the ground moving from tree to

tree, so they must have had to utilize all four of their extremities more often. As Aiello (1997) notes, knuckle-walking and knuckle-running are

quite taxing on a body. Ultimately, mutations coded for a semi-erect

posture, and other mutations coded for an erect posture. Such fortuitous

mutations would have been fi tting for a savanna lifestyle where one could

be more effi cient at foraging, scavenging, and running away from predators

if one were on two legs, freeing up the arms for other activities.

Along with bipedalism, it is generally agreed by biologists, anthropologists,

archeologists, and other researchers that a variety of factors contributed

to the evolution of the human brain. These factors include, but are

by no means limited to, such things as diversifi ed habitats, social systems,

protein from large animals, higher amounts of starch, delayed consumption

of food, food sharing, language, and toolmaking (Aboitiz, 1996; Aiello,

1996, 1997; Aiello & Dunbar, 1993; Allman, 2000; Byrne, 1995; Deacon,

1997; Donald, 1991, 1997; Gibson & Ingold, 1993; Lock, 1993; Calvin,

1998, 2001, 2004; Dawkins, 2005). It is not possible to get a complete

picture of the evolution of the brain without looking at all of these factors,

as brain development is involved in a complex coevolution with physiology,

environment, and social circumstances. And, most obviously, the

emergence of language in our species occupies a central place with respect

to our ability to fl ourish and dominate the earth (Tallerman, 2005; Christiansen

& Kirby, 2003; Deacon, 1997; Mithen, 1996; Aiello & Dunbar,

1993). However, I wish to focus on toolmaking as essential in the evolution

of the brain and visual system. I do this for three reasons.

First, toolmaking is the mark of intelligence that distinguishes the Australopithecine

species from the Homo species in our evolutionary past. Homo

habilis was the fi rst toolmaker, as the Latin name (handy-man) suggests.

Second, tools offer us indirect—but compelling—evidence that psychological

states emerged from brain states. In trying to simulate ancient toolmaking

techniques, archeologists have discovered that certain tools only can

be made according to mental templates, goal formations, and scenarios, as

Pelegrin (1993), Isaac (1986), and Wynn (1979, 1981, 1991, 1993) have

demonstrated. Finally, as I show, the evolution of toolmaking parallels the

evolution of the visual system from noncognitive visual processing to

conscious cognitive visual processing in terms of scenario visualization. Let

me explicate these three points.

As was noted above, Proconsul most likely had a brain similar to that of

a monkey. The Australopithecine brain was not much larger but probably

had all of the same neural connections as that of a present-day chimpanzee.

Thus, we can look to the chimpanzee and its usage of tools as an

indicator of what Australopithecine tool usage may have been like. Chimps

The Evolution of the Visual System and Scenario Visualization 111

can strip leaves from branches and use these branches to fi sh for termites,

knock fruit from a tree, or hit other chimps. They also use leaves to construct

little makeshift baskets to carry food, protect themselves from rain,

or scoop up water to drink. Further, they use stones to crack open nuts

and other husks in order to extract food (McGrew, 2004; Byrne, 1995,

2001; Byrne & Whiten, 1988; Griffi n, 1992; Stanford, 2000). It is likely that

the Australopithecines did similar things.

The fi rst stone artifacts, Oldowan stones, date to between 3 and 2 mya

and usually are associated with Homo habilis. They consist of fl akes, choppers,

and bone breakers that likely were used to break open the bones of

animals in order to get at the protein-rich marrow (Pelegrin, 1993; Isaac,

1986; Wynn, 1981; Wynn & McGrew, 1989; Mithen, 1996). Most probably,

Homo habilis had to wait until other bigger animals killed their prey and

feasted before they went in and scavenged what was left of the carcass.

The key innovation has to do with the technique of chopping stones to

create a chopping or cutting edge. Typically, many fl akes and the like were

struck from a single core stone, using a softer hammer stone to strike the

blow.

Here, we have the fi rst instance of making a tool to make another tool,

and it is arguable that this technique is what distinguishes ape-men from

apes. Another way to put this is that chimps and Australopithecines used

the tools they made but did not use these tools they made to make other

tools. Thus, the distinction is between a tool user who has made a certain

tool A to serve some function (e.g., Australopithecines and chimps) and a

toolmaker who has made a certain tool A to serve the specifi c function of

making another tool B to serve some function (e.g., Homo habilis).

Also, as has been noted, the brain of Homo habilis was approximately

700 cm in volume, almost twice the size of the Australopithecine’s brain. It

is likely that this increase in brain size contributed to the move from tool

usage to toolmaking. What this means is that, through the combined

factors of genetic mutation and environmental pressures, the brain evolved

the capacity for more complex connections and capacities, setting up the

conditions for the possibility of toolmaking. Those hominins who were either

lucky enough or resourceful enough to discover the benefi ts of toolmaking

began to do so and survived to reproduce more “crafty” hominins like

themselves.

The Acheulian tool industry consisted of axes, picks, and cleavers. It fi rst

appeared around 1.5 mya and usually is associated with Homo erectus or

Homo ergaster. The key innovations include the shaping of an entire stone

to a stereotyped tool form, as well as producing a symmetrical (bifacial) cutting edge by chipping the stone from both sides. It seems that the same

tools were being used for a variety of tasks such as slicing open animal

skins, carving meat, and breaking bones (Pelegrin, 1993; Isaac, 1986;

Mithen, 1996; Wynn, 1979). Consistent with the increase in the complexity

of toolmaking, the brain of Homo erectus increased to 900 cm in volume,

up 200 cm from Homo habilis. The Oldowan and Acheulian industries are

part of the time period commonly referred to as the Lower Paleolithic.

The Acheulian industry stayed in place for over a million years. The next

breakthrough in tool technology was the Mousterian industry that arrived

on the scene with the Homo neandertalensis lineage, near the end of the

Homo heidelbergensis lineage, around 300,000 ya. Mousterian techniques

(also called Levallois methods) involved a more complex three-stage process

of constructing (1) the basic core stone, (2) the rough blank, and (3) the

refi ned fi nalized tool. Such a process enabled various kinds of tools to be

created, since the rough blank could follow a pattern that ultimately would

become fl ake blades, scrapers, cutting tools, serrated tools, or lances.

Further, these tools had wider applications as they were being used with

other material components to form handles and spears, and they were

being used as tools to make other tools, such as wooden and bone artifacts

(Pelegrin, 1993; Isaac, 1986; Mithen, 1996; Wynn, 1981, 1991). Again,

consistent with the increase in complexity of toolmaking, the brain of

Homo heidelbergensis and Homo neandertalensis increased to 1,200 cm and

1,500 cm in volume, respectively, up 300 to 600 cm from Homo erectus. The

Mousterian industry is part of the time period commonly referred to as the

Middle Paleolithic.

By 40,000 ya, some 80,000 years after anatomically modern Homo sapiens

evolved, we fi nd instances of human art in the forms of beads, tooth necklaces,

cave paintings, stone carvings, and fi gurines. This period in tool

manufacture is known as the Upper Paleolithic industry, and it ranges from

40,000 ya to the advent of agriculture around 12,000 ya. Sewing needles

and fi sh hooks made of bone and antlers fi rst appear, along with fl aked

stones for arrows and spears, burins (chisel-like stones for working bone

and ivory), multibarbed harpoon points, and spear throwers made of

wood, bone, or antler (Pelegrin, 1993; Isaac, 1986; Mithen, 1996; Wynn,

1991). The human brain during this period was about the same size as it

is today, between 1,200 and 1,400 cm in volume.

In the previous chapter, I distinguished four levels of visual processing.

The fi rst level is a noncognitive visual processing that occurs at the lowest

level of the visual hierarchy associated with the eye, LGN, and primary

visual cortex. The second level of visual processing is a cognitive visual

The Evolution of the Visual System and Scenario Visualization 113

processing that occurs at a higher level of visual awareness associated with

the what and where visual unimodal areas. As I noted, the move from

noncognitive visual processing to cognitive visual processing is a move

from the purely neurobiological to the psychoneurobiological dimension

of the brain. The third level of visual processing is a cognitive visual processing

that consists of the integration of visual information in the visual

unimodal association area. The fourth level of visual processing is a conscious

cognitive visual processing that occurs at the highest level of the

visual hierarchy concerned with the multimodal areas, frontal areas, and,

most probably, the summated areas of the cerebral cortex.

The question now becomes this: What level of visual processing did these

early hominins achieve in light of the size of their brains and the tools

they constructed? Given the neural connections of present-day chimps, as

well as the eye-socket formations and endocasts of Australopithecines, it is

clear that both have (had) noncognitive visual processing. Also, given that

chimps are aware of and attend to visual stimuli, it is likely that they, along

with Australopithecines, have (had) cognitive visual processing. But can

these species be said to have conscious cognitive visual processing? Possibly,

to a certain extent. However, it is arguable that what counts against such

species having full conscious cognitive visual processing is a lack of

advanced forms of toolmaking, like those found in the Upper Paleolithic

industry. There seems to be a direct connection between advanced forms

of toolmaking and conscious visual processing. What exactly is that

connection?

The hominin line diverged from the common ancestor of African apes

some 6 mya. As was noted above, the brains of Australopithecines got no

bigger than that of a chimpanzee. Therefore, from research on primates

and monkeys, coupled with the archeological and geological data, we have

an idea of what the brain and visual system of Australopithecines may have

looked like and how they would have performed (Dunbar, 1988; see the

articles in Berthelet & Chavaillon, 1993). The neurophysiology and lifestyle

of Early Australopithecines, like A. anamensis, were probably similar to

those of present-day chimps.

However, the climate in Africa slowly changed. Approximately 8 mya,

present-day India (which was separate from Asia prior to this time) butted

up against Asia and formed the Himalayan mountains, thereby robbing

Africa of excess amounts of water. This climatic change caused eastern

Africa to be transformed from predominantly forested environments, to

savanna-like environments of forest and open range, to open range environments

with little or no forestation (Calvin, 2001, 2004; Potts, 1996;

Eldredge, 2001). Daly & Wilson (1999), Foley (1995), and Boyd & Silk

(1997) have shown that the Pleistocene epoch did not consist of a single

hunter–gatherer type of environment but was actually a constellation of

environments that presented a host of challenges to the early hominin

mind. The climate shift in Africa from jungle life to desert/savanna life

forced our early hominins to come out of the trees and survive in totally

new environments (Tattersall, 2001; Calvin, 2004; Aiello, 1997; Fleagle,

1999).

If the Australopithecines wanted to continue to live a life in the trees, they

would have had to spend more time on the ground moving from tree to

tree, so they must have had to utilize all four of their extremities more often. As Aiello (1997) notes, knuckle-walking and knuckle-running are

quite taxing on a body. Ultimately, mutations coded for a semi-erect

posture, and other mutations coded for an erect posture. Such fortuitous

mutations would have been fi tting for a savanna lifestyle where one could

be more effi cient at foraging, scavenging, and running away from predators

if one were on two legs, freeing up the arms for other activities.

Along with bipedalism, it is generally agreed by biologists, anthropologists,

archeologists, and other researchers that a variety of factors contributed

to the evolution of the human brain. These factors include, but are

by no means limited to, such things as diversifi ed habitats, social systems,

protein from large animals, higher amounts of starch, delayed consumption

of food, food sharing, language, and toolmaking (Aboitiz, 1996; Aiello,

1996, 1997; Aiello & Dunbar, 1993; Allman, 2000; Byrne, 1995; Deacon,

1997; Donald, 1991, 1997; Gibson & Ingold, 1993; Lock, 1993; Calvin,

1998, 2001, 2004; Dawkins, 2005). It is not possible to get a complete

picture of the evolution of the brain without looking at all of these factors,

as brain development is involved in a complex coevolution with physiology,

environment, and social circumstances. And, most obviously, the

emergence of language in our species occupies a central place with respect

to our ability to fl ourish and dominate the earth (Tallerman, 2005; Christiansen

& Kirby, 2003; Deacon, 1997; Mithen, 1996; Aiello & Dunbar,

1993). However, I wish to focus on toolmaking as essential in the evolution

of the brain and visual system. I do this for three reasons.

First, toolmaking is the mark of intelligence that distinguishes the Australopithecine

species from the Homo species in our evolutionary past. Homo

habilis was the fi rst toolmaker, as the Latin name (handy-man) suggests.

Second, tools offer us indirect—but compelling—evidence that psychological

states emerged from brain states. In trying to simulate ancient toolmaking

techniques, archeologists have discovered that certain tools only can

be made according to mental templates, goal formations, and scenarios, as

Pelegrin (1993), Isaac (1986), and Wynn (1979, 1981, 1991, 1993) have

demonstrated. Finally, as I show, the evolution of toolmaking parallels the

evolution of the visual system from noncognitive visual processing to

conscious cognitive visual processing in terms of scenario visualization. Let

me explicate these three points.

As was noted above, Proconsul most likely had a brain similar to that of

a monkey. The Australopithecine brain was not much larger but probably

had all of the same neural connections as that of a present-day chimpanzee.

Thus, we can look to the chimpanzee and its usage of tools as an

indicator of what Australopithecine tool usage may have been like. Chimps

The Evolution of the Visual System and Scenario Visualization 111

can strip leaves from branches and use these branches to fi sh for termites,

knock fruit from a tree, or hit other chimps. They also use leaves to construct

little makeshift baskets to carry food, protect themselves from rain,

or scoop up water to drink. Further, they use stones to crack open nuts

and other husks in order to extract food (McGrew, 2004; Byrne, 1995,

2001; Byrne & Whiten, 1988; Griffi n, 1992; Stanford, 2000). It is likely that

the Australopithecines did similar things.

The fi rst stone artifacts, Oldowan stones, date to between 3 and 2 mya

and usually are associated with Homo habilis. They consist of fl akes, choppers,

and bone breakers that likely were used to break open the bones of

animals in order to get at the protein-rich marrow (Pelegrin, 1993; Isaac,

1986; Wynn, 1981; Wynn & McGrew, 1989; Mithen, 1996). Most probably,

Homo habilis had to wait until other bigger animals killed their prey and

feasted before they went in and scavenged what was left of the carcass.

The key innovation has to do with the technique of chopping stones to

create a chopping or cutting edge. Typically, many fl akes and the like were

struck from a single core stone, using a softer hammer stone to strike the

blow.

Here, we have the fi rst instance of making a tool to make another tool,

and it is arguable that this technique is what distinguishes ape-men from

apes. Another way to put this is that chimps and Australopithecines used

the tools they made but did not use these tools they made to make other

tools. Thus, the distinction is between a tool user who has made a certain

tool A to serve some function (e.g., Australopithecines and chimps) and a

toolmaker who has made a certain tool A to serve the specifi c function of

making another tool B to serve some function (e.g., Homo habilis).

Also, as has been noted, the brain of Homo habilis was approximately

700 cm in volume, almost twice the size of the Australopithecine’s brain. It

is likely that this increase in brain size contributed to the move from tool

usage to toolmaking. What this means is that, through the combined

factors of genetic mutation and environmental pressures, the brain evolved

the capacity for more complex connections and capacities, setting up the

conditions for the possibility of toolmaking. Those hominins who were either

lucky enough or resourceful enough to discover the benefi ts of toolmaking

began to do so and survived to reproduce more “crafty” hominins like

themselves.

The Acheulian tool industry consisted of axes, picks, and cleavers. It fi rst

appeared around 1.5 mya and usually is associated with Homo erectus or

Homo ergaster. The key innovations include the shaping of an entire stone

to a stereotyped tool form, as well as producing a symmetrical (bifacial) cutting edge by chipping the stone from both sides. It seems that the same

tools were being used for a variety of tasks such as slicing open animal

skins, carving meat, and breaking bones (Pelegrin, 1993; Isaac, 1986;

Mithen, 1996; Wynn, 1979). Consistent with the increase in the complexity

of toolmaking, the brain of Homo erectus increased to 900 cm in volume,

up 200 cm from Homo habilis. The Oldowan and Acheulian industries are

part of the time period commonly referred to as the Lower Paleolithic.

The Acheulian industry stayed in place for over a million years. The next

breakthrough in tool technology was the Mousterian industry that arrived

on the scene with the Homo neandertalensis lineage, near the end of the

Homo heidelbergensis lineage, around 300,000 ya. Mousterian techniques

(also called Levallois methods) involved a more complex three-stage process

of constructing (1) the basic core stone, (2) the rough blank, and (3) the

refi ned fi nalized tool. Such a process enabled various kinds of tools to be

created, since the rough blank could follow a pattern that ultimately would

become fl ake blades, scrapers, cutting tools, serrated tools, or lances.

Further, these tools had wider applications as they were being used with

other material components to form handles and spears, and they were

being used as tools to make other tools, such as wooden and bone artifacts

(Pelegrin, 1993; Isaac, 1986; Mithen, 1996; Wynn, 1981, 1991). Again,

consistent with the increase in complexity of toolmaking, the brain of

Homo heidelbergensis and Homo neandertalensis increased to 1,200 cm and

1,500 cm in volume, respectively, up 300 to 600 cm from Homo erectus. The

Mousterian industry is part of the time period commonly referred to as the

Middle Paleolithic.

By 40,000 ya, some 80,000 years after anatomically modern Homo sapiens

evolved, we fi nd instances of human art in the forms of beads, tooth necklaces,

cave paintings, stone carvings, and fi gurines. This period in tool

manufacture is known as the Upper Paleolithic industry, and it ranges from

40,000 ya to the advent of agriculture around 12,000 ya. Sewing needles

and fi sh hooks made of bone and antlers fi rst appear, along with fl aked

stones for arrows and spears, burins (chisel-like stones for working bone

and ivory), multibarbed harpoon points, and spear throwers made of

wood, bone, or antler (Pelegrin, 1993; Isaac, 1986; Mithen, 1996; Wynn,

1991). The human brain during this period was about the same size as it

is today, between 1,200 and 1,400 cm in volume.

In the previous chapter, I distinguished four levels of visual processing.

The fi rst level is a noncognitive visual processing that occurs at the lowest

level of the visual hierarchy associated with the eye, LGN, and primary

visual cortex. The second level of visual processing is a cognitive visual

The Evolution of the Visual System and Scenario Visualization 113

processing that occurs at a higher level of visual awareness associated with

the what and where visual unimodal areas. As I noted, the move from

noncognitive visual processing to cognitive visual processing is a move

from the purely neurobiological to the psychoneurobiological dimension

of the brain. The third level of visual processing is a cognitive visual processing

that consists of the integration of visual information in the visual

unimodal association area. The fourth level of visual processing is a conscious

cognitive visual processing that occurs at the highest level of the

visual hierarchy concerned with the multimodal areas, frontal areas, and,

most probably, the summated areas of the cerebral cortex.

The question now becomes this: What level of visual processing did these

early hominins achieve in light of the size of their brains and the tools

they constructed? Given the neural connections of present-day chimps, as

well as the eye-socket formations and endocasts of Australopithecines, it is

clear that both have (had) noncognitive visual processing. Also, given that

chimps are aware of and attend to visual stimuli, it is likely that they, along

with Australopithecines, have (had) cognitive visual processing. But can

these species be said to have conscious cognitive visual processing? Possibly,

to a certain extent. However, it is arguable that what counts against such

species having full conscious cognitive visual processing is a lack of

advanced forms of toolmaking, like those found in the Upper Paleolithic

industry. There seems to be a direct connection between advanced forms

of toolmaking and conscious visual processing. What exactly is that

connection?