Archeological evidence suggests but does not prove that trade took place between human groups of homo erectus prior to the emergence of homo sapiens, in other words between 1.4 million years ago and roughly 300,000 years ago. These groups were kin-groups with a hunter-gatherer and sometimes nomadic life-style.
It is tempting to suppose that the gradual expansion of homo erectus from its African home to coverage of most of Europe and Asia would have created many demands for trade. If a sub-group splits off from a group whose current territory includes a stone quarry (for axe-heads) and migrates to an area where game is plentiful but there are no quarries, it is easy to see that a trading network will come into existence to maintain the supply of axe-heads to the sub-group.
Sharp 9 describes the Stone Age Yir Yoront tribe living in the north of Australia, who trade (or used to trade) sting-ray barbs for stone axes produced 400 miles to the south, through a long line of intermediate tribes.
Among surviving Stone-Age tribal cultures, division of labour seems to take place to a marked degree even within an area in which groups are in constant touch with one another, and even in the absence of environmental features to drive it. Groups which develop and practise different skills will inevitably need to trade with each other; the suggestion here is that the propensity to trade may be the cause rather than the result of division of labour, with the benefit being a more harmonious, or at least less bloodthirsty system of communal inter-group alliances. Matt Ridley calls trade 'the beneficent side of human groupishness'.
The trust that is displayed in reciprocal exchanges, especially when the second half of an exchange is deferred, owes much to its origins within the kin-group, to the extent that putative trading partners often attempt to find a basis of trust by exploring possible relationships, even if distant ones. Although this behaviour is most marked in tribes which have not departed far from the kin-group model, it is an everyday occurrence among modern humans, who eagerly seize upon any basis for relationship with people they meet, such as common friends or common origins (membership of the same group, in other words) and feel much reassured when such a relationship is found. While this doesn't damage the concept of reciprocity, it does emphasize the extent to which group membership is helpful in creating the trust needed for successful trading.
Healey 10 studied Kundagai Maring trading patterns in Papua New Guinea showing that among un-related traders, immediate exchange took place 483 times as against 35 cases of delayed exchange, while among related traders, there were 697 cases of delayed exchange as against 71 cases of immediate exchange. Healey notes: 'The search for kinship ties between erstwhile strangers introduces moral principles that should obtain between the parties'.
As explained in the Introduction, those who practised trade in early human kin-groups certainly understood it as a group activity, or if you wish, an activity undertaken on behalf of the group, or between groups. This was the prevailing cultural model of trade until very recently, and is certainly how it was thought about by mediaeval traders in the guild system. Although to the modern mind trading often presents itself first and foremost as an individual activity, its communal origins can be seen preserved in joint corporate forms and partnerships. This is important to an understanding of why trading can be conducted very satisfactorily under a rule-based international order, and of why nation states have more often been the enemy rather than the friend of traders.
9 Sharp, L Steel Axes for Stone-Age Australians, Human Problems in Technological Change, pp 69-92, Russell Sage Foundation, New York
10 Healey, C (1984) Trade and Sociability: Balanced Reciprocity as Generosity in the New Guinea Highlands, American Ethnologist, 11, 42-60