What do you know of the world's oldest profession?

Up to now, when someone referred to the term ‘the oldest profession’, I interpreted it as you would do. For, by now I had come to know what, the user of the phrase, wanted me to understand. But, recently I came across another article which claims to challenge this. It says that ‘commodities trading’ is the one which should be holding the title. The title goes as:

“The idea of a commodity future in the true sense is not an invention of the 19th and 20th centuries but goes back over two thousand years. One of the earliest recorded types of commodity derivative was in options. Around 500 BC, a copper mining industry developed in the Mediterranean. When Phoenician traders had guaranteed a sale of material, space was limited on board the Greek ships to deliver their goods. To avoid this problem and put themselves in a position to trade, the Phoenicians bought options on vessel space to guarantee their business, at the same time allowing them to fix the price the customer would pay for the copper.”

A look at the Wikipedia entry for prostitution gives:

“Prostitution is often described as "the world's oldest profession." It has been thought prostitution (at least in the modern sense) cannot have emerged before the emergence of money, which can only have taken place after the emergence of several trades, and it has been claimed that midwifery, or perhaps gardening or teaching, are really the world's oldest professions. However, prostitution in exchange for goods or services may have been common for many thousands of years and may date to early man. Additionally, prostitution has been noted in Bonobo chimpanzee behavior based around access to food and gifts of food, and in penguins in regard to access for suitable stones for nest building. Until the age of industrialization the world was basically agrarian, so goods and services were most often obtained by barter.”

I think the claim makes sense, at least for the case of humans. If the concept of prostitution to be the oldest profession is based on the assumption that it may had been used for exchange of goods, the exchange (or trade) of these commodities were taking place. In addition, commodities were considered to be kind of important, as people were virtually agreeing to do anything for this. So, the concept of ‘commodities trading’ has to be born before the so called ‘the world's oldest profession’.