A There are, according to current scholarship, 160 existing portraits by Francisco de Goya - about a third of his painted output. The real number, though, is much greater since there are no pure landscapes in Goya's work, in that everything he ever painted deals with people. In the work of no other great portraitist are a nation's people, history, traumas, folk traditions, and superstitions so comprehensively and relentlessly captured. His subject was a good one since Goya lived in interesting times: his lifetime was a period that saw Spain pass through the effects of the French Revolution, the Napoleonic wars, and the restoration of the monarchy; it was ruled by a succession of authoritarian and liberal governments; and was simultaneously marked by the Enlightenment. Put his work together - the public and private paintings, the personal drawings and sketches, and the unsettling and sinister etching series - and what you have is a portrait in the round of Spain itself.

B His work as a portraitist has its origins in the 45 tapestry cartoons he painted after he moved to Madrid in 1775. Although his designs don't show portraits, they do show types - the majos and majas who gave Madrid its street swagger, peasants and rich men, courting couples, singers, hunters, children, and young men and women playing blind man's buff or tossing a mannequin into the air. The pictures have a light, rococo palette and the faces are individualised without being those of individuals. But in them, Goya practised poses and groupings and a way of handling light on and around figures that was to be invaluable.

C The tapestry designs also show social roles rather than the people inhabiting them, but when it came to painting portraits proper, Goya would turn this on its head. His greatest strength as a portraitist is that regardless of the status of the sitter, be they a king and queen, the Duke of Wellington, or a doctor or writer, it was the person he showed first and their position second. It was this trait, most apparent in his royal portraiture, that has led him to be seen as satirising the Bourbon monarchy rather than as a painter who depicted what he saw without showing obeisance to the usual flattering conventions. In Robert Hughes's phrase, he did not 'pay reflexive homage to authority' but instead walked a fine line between respect and truth.

D Goya's success was rapid; in 1785 he was made deputy director of painting at the Royal Academy (his main message to his students was subversive - 'there are no rules in painting') and in 1786 became pintor de cámara, required to paint 'works required for royal service'. He immediately spent some of his 15,000-reales salary on a two-wheeled gig (one of only three in Madrid) which he promptly crashed on his first outing. His amour propre untouched, he wrote to his childhood friend Martín Zapater: 'I have now established an enviable way of living: I do not wait on anyone in antechambers, and if anyone wants anything from me they must come to me; I have made myself more in demand and unless it is a person of rank or at the request of a friend I would do nothing for anyone...'

E Part of the reason for his success was that, unlike Gainsborough, for example, he did not resent portraiture as an economically necessary chore that ate away at the time he could devote to higher art. He embraced the genre as a means of exploring human character. This genuine interest allowed him to penetrate the facade of his sitters, capturing not just their likeness but their psychological state. His portraits from the 1790s, particularly of the royal family, are masterclasses in this approach. He presented them with a stark realism that was unprecedented, grouping them in a way that highlighted their familial dynamics and individual personalities, however flawed or ordinary they might appear.

F This commitment to psychological truth became even more pronounced following his near-fatal illness in 1793, which left him deaf. Isolated from the world of sound, Goya’s focus turned inwards, and his work grew darker and more introspective. The light rococo tones of his tapestry cartoons gave way to a richer, somber palette and a dramatic use of chiaroscuro. His portraits from this period, such as those of the Duchess of Alba, are charged with a complex mixture of intimacy, mystery, and power. The line between observer and subject seemed to dissolve, as Goya used the portrait not for public glorification but as a form of private, almost philosophical, inquiry.

G Ultimately, Goya’s career traces the arc of Spain’s tumultuous age. The enlightened optimism of his early court paintings gradually soured into a profound disillusionment, vividly recorded in his later, so-called 'Black Paintings'. These murals, painted directly onto the walls of his country house, are a far cry from the formal portraits of princes and dukes. They depict haunting, mythological scenes and grotesque figures, reflecting the despair and chaos of a nation ravaged by war and repression. In this final phase, the portrait of Spain was no longer found in the faces of individuals, but in the tormented soul of its people.

Charles Darwin, the brilliant anthropologist and creator of the theory of evolution, is not normally associated with the modern business world. Nevertheless, Darwinian evolutionary theory is the foundation of a new wave of ideas about human behavior in general and particularly the way people behave in the workplace; these ideas have given the title of 'evolutionary psychology'.

Evolutionary psychology revolves around the notion that our brains, like our bodies, have an inherited evolutionary design that has scarcely changed for 10,000 years. As respected evolutionary psychology experts Leda Cosmides and John Tooby comment, our modern skulls house a Stone Age mind.' The US biologist Edward O Wilson sees evolutionary psychology as being a discipline which is based on both socio-biology, which is the study of the biological basis of social behavior, and psychology, which is the systematic study of human behavior.

Nigel Nicholson, an organisational psychologist from the London Business School, is a strong supporter of evolutionary psychology and on this subject has published Managing the Human Animal. His book takes the reader on a journey from the Stone Age plains of the savannah to the modern office, and includes a discussion of Darwinism and behavioural psychology together with a dissection of dysfunctional organisational behavior. It is an effective approach explaining why people behave as they do, particularly at work. Evolutionary psychology is increasingly being cited in management circles, where managers are trying to understand puzzling aspects of human behaviour and by doing so improve the workplace. Nicholson believes that evolutionary psychology can help managers understand what goes wrong in organisational life and what they can do about it.

Nicholson maintains that evolutionary psychology dismisses the long-held assumption that our minds are like blank pages just waiting for culture and experience to write on them and shape our nature. He points out that sophisticated research shows the brain actually houses a store of knowledge when we are born, and now genetic research is establishing there are certain genes that account for abilities, tastes and tendencies. The stored knowledge in the human brain has not changed much since the Stone Age. As Tooby and Cosmides stress, there have not been enough generations for a brain that is well adapted to our post-industrial life to evolve through natural selection.

The evolutionary psychology version of human nature revolves around some key elements which we have inherited from our hunter-gatherer minds. One key element is emotion. Emotion was originally essential to keep early man alive and safe from predators. Emotion was, and continues to be our radar, guiding us throughout today's techno-defined business world. Despite this, the business world emphasises rational not emotional behaviour, and does not admit the importance of emotion. We still use the emotional part of our minds to make sense of other people's behaviour and to create an impression, so we can often be taken in by appearances. This mental predisposition actually works best in small communities (the tribe), not in much larger environments filled with people we barely know (the modern workplace). Our minds naturally try to re-create our ancestral communities with networks of no more than 150 people, where there are clear hierarchies and leaders. As a consequence, it takes very little to trigger people's innate distrust of others because our safety in antiquity depended on supporting our near family and friends whom we valued more than other people.

So what advice does Nicholson have for the corporate world? He thinks that by knowing the reasons for people's behaviour it is possible to mould corporate environments into places that have more chance of working efficiently and being pleasant places to work in. Nicholson admits that not everybody in the business world agrees with his belief in the effectiveness of evolutionary psychology in the workplace. One group that resists the theory of evolutionary psychology is young MBA graduates who are just beginning their careers and feel that evolutionary psychology will make their lives at work more difficult. Older and wiser executives point out that they still tend to cling to the idea of a magic formula to bring people into line with corporate strategy. But that is back-to-front thinking according to Nicholson, who contends that we should be reinventing our business structures, not our fundamental human nature.

At the end of his book, Nicholson gives his forecast of what will and will not change in the business world. He believes that most people will still prefer more traditional forms of work and throughout their lives will continue to aim at lifelong status advancement. He also maintains that the line between work and home will be less defined, but that people will prefer traditional working patterns if working from home leaves them isolated from their work community. He doubts that the high-tech ideas of virtual companies will ever be very successful because people will still want to meet each other face-to-face. Nicholson describes his ideal organisation in the future: it would be decentralized, with small sub-units; the staff would be from diverse backgrounds and be allowed a high degree of self-determination. New endeavours and creativity would replace systems and rationality. Nicholson acknowledges that there is a long way to go in terms of the translation of his ideas of evolutionary psychology into practical propositions, but he is confident more and more people will come round to his way of thinking.