Some of its very know effects by nowadays where already descript although being unknown the plethora of effects that are available today (in Galen passages some effects where cited like difficult to digest, cause pain in the stomach, migraine, spoils humors and also produced an altered state of mind in some people, particularly when it was smoked and not eaten. In equal way, Greek people knew about its vapors, and obviously, about its special effects, and the fact that roughly nobody described abuse of this stupefacient in a straight line was maybe due to its rarity (cannabis was not believed to be originally from Greek) or its abnormal consumption (22).

Cannabis is part of THC drugs (Tetrahydrocannabinols). Its effects are well described: when the drug is smoked the effects appear quicker than when ingested, being the primary effects euphoria, relaxation and changes in the perception (23). In heavy consumers more prominent delusions can occur, time notion are modified, the short term memory is affected, mental processes become confused, the person can forget the contents of conversations and be not able to communicate accurately; ultimately, other negative effect are paranoia, respiratory problems, dryness in mouth, cardiac acceleration, psychological dependence and, if the consumer have tendency to develop neuroses and psychoses, the use of cannabis can unchain the problem (23).

Morphine (name in honor to Morfeo, God of the dreams), was isolated of the opium at the beginning of century XIX by the German Fiedrich William Sertüner and happened to replace (along with codeine) the opium in the medical treatments, specially after the introduction of hypodermic injection like therapeutic, in 1855 (2,7). In 1874, was created the first semi synthetic opiate, diacetylmorphine, also well-known as heroin. It was commercialized by Bayer as substitute of the opium and morphine in the detox programs; its effects as a potent pain killer and stimulating effect lead to widespread commercialization and only many years later the commercialization for this aim was interrupted (12). The heroin began to become popular like recreational drug in the United States and England first and, later, in almost the entire world, being sought as the symbol of pernicious effects of drugs (24).

Ecstasy was one of the most popular illegal psychotropic drugs back to the past 1980 era (25). One of the most used drugs amongst youngsters that although most of medical references about de origins is methylenedioxymethamphetamine (MDMA, ecstasy) that makes references of its development as an appetite suppressor, by the German pharmaceutical company Merck in 1912, it is nothing but a common error (26). Although MDMA had been developed in 1912 the first known study in humans was published in 1978, by Shulgin et al. about chemistry, kinetics, dosage, and psychotropic effects (27-28). Only in 1984 it was baptized as “Ecstasy” in California, USA (26).

What about cocaine? In America, the Inca empire (Andean) produced three annual harvests from cocaine leaf (erythroxilum cocaine lam) which were used as analgesic and energizing of daily use, specially due to fatigue produced by height; in the Aztec society, was also used the ingestion of the so called teonanacati fungus and the consumption of peyote with religious aims (6). The leaf of Cocaine (Erythroxylon Cocaine, of Linnaeus), overcomes its beginnings in the historical knowledge by year 2000 b.C., being found artifacts and instruments for its mastication in Chilean and Peruvian coasts; the word Cocaine comes from Khoca that means literally “tree” or “plants” (14), and when it emerges in all his splendor in the pre-Columbian times, locating itself like the center of the religious and social system of the Incas, for whom the plant was a divine gift (29). Other authors states that the use of the stimulating cocaine in America is as old as the use of the alcohol, opium and the cannabis in the old continent and Asia, so that cocaine leaves already were chewed in the Andean region from approximately 5,000 b.C.(30). Erythroxilum cocaine grew at the beginning of wild way but it began to be cultivated in the century X a.C., by the Chibcha Indians of Colombia, that later spread it to south, being used in sacred rituals and medicine procedures (31). In Inca culture where mastication of Cocaine leaf was mainly reserved for aristocracy and the sacerdotal body, except for sometimes specific rituals or in some initiate processes, and the own Americus Vespucci in 1499 is noticed of the behavior of some Indians of Venezuela coast, apparently raised and without fatigue in spite of the work (14).

Before the era of great navigations in century XVI cocaine was not well-known in other places of the world. When the Spaniards arrived, they were surprised with the effects of the leaves chewed by the workers. At a first moment, by religious reasons, they tried to prohibit it but later they used it like stimulating in the operation of the silver mines (2). The consumption by American Natives was attacked and condemned in the first celebrated Ecclesiastical Assembly in Lima in the year of 1551, once it was considered to be related to idolatry and witchcraft (32). It is praised and recommended by their active principle - the cocaine - and their pharmacological effects at the end of century XIX, when Sigmund Freud and Halsted and Hall, used it in their experiments of psychopharmacology and local anaesthesia, respectively (32-33).

Amphetamine is a chemical derivative of ephedrine, synthesized for the first time in 1887 by Rumanian chemistry L. Edeleano, which baptized the substance as phenilisopropilamine. The experimental medical use of amphetamines began in 1920. The role of World War II that lead to its administration to the soldiers in a massive form, with the objective to fight the fatigue and to maintain them alert (2). Almost all the armies used them. For instance, the American army distributed more than 180 million tablets to its combatants; amphetamines also have been used like an agent to improve physical and cognitive performance (doping effects) (2).

LSD was accidentally discovered by Swiss chemistry Albert Hoffman in 1938 when it tried to find an analogous substance to stimulate circulatory system, being commercialized by Sandoz factory under the name of Delycid, with the alleged objective of facilitate psychotherapy and to fight some upheaval like chronic alcoholism, sexual anomalies, etc.; when it was verified that the drug produced unforeseeable effects, it was finally forbidden (6).

At this point, let us remind the title of this paper: Origins of Addictive Behavior: nature or nurture? And let us think a little about it.

Some authors present a recent review about the denominated “paradox of drug reward in human evolution” and the evaluation of the paradox between evolutionary biology’s punishment model and neurobiology’s reward model (34).

The current existing models of drug reward have effectively bypassed the paradox by ignoring the evolved function of plant drugs and the probable co-evolution of plant defensive compounds and herbivore nervous systems. The principal conclusions was that there are some major assumptions underlying the current evolutionary reward models that should take into that:

a) “drugs are an evolutionary novelty;
b) humans (and mammals) are inherently vulnerable;
c) and hedonic reward best characterizes the psychological and physiological responses to drug exposure” (34).

They consider the contradictory evidence that shows that most of abuse drugs are derived from toxic elements, developed to be toxic and avoid and repeal enemies (e.g Butolin Toxine) (34). Also, the authors suggest that, as an hypothesis that the nature of human substance abuse could have evolved in order to exploit antiparasitic property of plant toxins, amongst other possibilities. Independently of the best hypothesis found, they suggest more and deeper neurochemichal research to explain the apparent tendency for humankind drug abuse (34).

Considering the distribution of drugs in natural environments in ancestral ages, if we consider that resources were limited and so probably the overactivity of salient (wanting) behavior. So, there is no reason to postulate the development of dopaminergic reward cortico-mesolimbic system in terms of a “built-in regulatory system of salience” (35). By that reason, the author postulate that factors like genetic and environmental ones could have no consequences in ancient environments, because of their limitations. This could be a factor that could have leaved us more vulnerable to addictive behavior, mostly, according to the author, the development of ancient psychotropic plant chemicals (35).

We present a table I with some landmarks of evolutionary addictive behavior and drug discover.

Table 1. Landmarks on addictive behavior (35)

a) Archaeological records indicate the presence of psychotropic plants and drug use in ancient civilizations as far back as early hominid species about 200 million years ago.
b) Roughly 13,000 years ago, the inhabitants of Timor commonly used betel nut (Areca catechu), as did those in Thailand around 10,700 years ago.
c) At the beginning of European colonialism, and perhaps for 40,000 years before that, Australian aborigines used nicotine from two different indigenous sources: pituri plant (Duboisia hopwoodii) and Nicotiana gossel. North and South Americans also used nicotine from their indigenous plants N. tabacum and N. rustica.
d) Ethiopians and northern Africans were documented as having used an ephedrine-analog, khat (Catha edulis), before European colonization.
e) Cocaine (Erythroxylum coca) was taken by Ecuadorians about 5,000 years ago and by the indigenous people of the western Andes almost 7,000 years ago. The substances were popularly administered through the buccal cavity within the cheek. Nicotine, cocaine, and ephedrine sources were first mixed with an alkali substance, most often wood or lime ash, creating a free base to facilitate diffusion of the drug into the blood stream. Alkali paraphernalia have been found throughout these regions and documented within the archaeological record. Although the buccal method is believed to be most standard method of drug administration, inhabitants of the Americas may have also administered substances nasally, rectally, and by smoking. Many indigenous civilizations displayed a view of psychotropic plants as food sources, not as external chemicals altering internal homeostasis.
f) The perceived effects by these groups were tolerance to thermal fluctuations, increased energy, and decreased fatigue, all advantageous to fitness by allowing longer foraging session as well as greater ability to sustain in times of limited resources.